The Following Tips and Information comes from the following thread on BikeForums.net:
Mounting & Gluing Tubulars Process Version 1:
1) Inflate tubular tire to 40psi without mounting to a rim/wheel. Leave in this state for 4-7 days.
2) Deflate tire and mount on rim without glue. Reinflate to 40psi and leave in this state for another 7-10 days.
3) After the second week the tire should be well stretched and much easier to handle when trying to install on the rim with glue.
4) A few days before you want to glue the tire on, put a layer of glue on the rim(s) you will be gluing the tire to.
5) Work in a well ventilated area, preferably a garage or somewhere else that a little mess won't be a huge problem. Wear thin vinyl or latex gloves to protect your skin. Be sure to have a clean rag and mineral spirits ready to clean any glue from the sidewalls or other areas not to be glued together. You will want to wipe up any extra glue immediately.
6) Deflate the tire, and put the stem of the tire through the valve hole of the rim. Make sure you have the tire oriented the way you want it. Once the tire is on the rim, sit in a char and hold the rim with the stem up. Grasp the tire about one spoke hole away from the stem and lift up. Squeeze a bit of glue onto the exposed sections of the rim. Move the glue tube around to get a light coating on the entire surface. Release the tire, being certain that the base tape is centered, rotate the rim two spoke holes, and repeat the process. Do this until you make it back to the stem.
7) If you get any glue on the tire, rim, spokes or yourself, wipe it off immediately. Use mineral spirits as necessary to clean the glue from any metal that it gets on.
8) Once you've completed the gluing, inflate to about 25 psi. If any glue oozes onto the tire or rim, wipe it off immediately. Also make any manipulations you may want to center the tire if it hasn't gone on quite as straight as you want. You may need to decrease the pressure in the tire to do this. After 30 minutes, inflate the tire to about 40 psi and let the rim sit over night.
Mounting & Gluing Tubulars Process Version 2 (the quick version):
1) Use a Plumber's Flux Brush(.25 cents) to brush the glue onto the Rim and Tire.
2) Let dry to a tack(about 20 minutes)
3) Assemble the tire and rim.
Mounting & Gluing Tubulars Process Version 3:
1. Stretch the tire. Ideally, put it on the rim and inflate to max pressure and leave it for 1 week. If its 8pm and you need to race on it the next morning, try this. With no air in it, try to get the tire to stretch onto the rim without too much resistance. It should go on snug but easily by hand, you shouldn't need a pry bar/ tire remover to get it on. If it goes on, good, proceed to step 2. If not, sit in a chair grab one end of the tire with both hands, hook the other end under your feet and progressively apply pressure to stretch the tire. Go slowly but you will likely have to apply a lot of force to stretch, just don't go ape and rip the tire apart. Stretch until it goes on just snug, but easily.
2. Prepare the rim. Rough up the rim with a wire brush or coarse grit sandpaper. Clean meticulously with brake parts cleaner. Put masking tape on the side of the rim where the brakes pads make contact. This will save at least minutes, if not hours, of cleaning and recleaning to get glue off the sides of the rims.
3. Apply the glue. Goober up both the rim and the tire and don't skimp on the glue! Hang them both up to dry overnight.
4. Put the tire on the rim. The glue is contact cement, so remember, once you touch the parts together they STICK. Put just enough air in the tire so it barely holds its shape, put the valve in the rim. With the valve at 12 oclock, put the rim on the floor perpendicular to the floor. Grab the tire with both hands, each hand about 1 foot from the valve. Now pull the tire apart and simultaneously push down and place the tire on the rim. The idea is to stretch it is much as possible before you put it on the rim. Repeat until you get about 1/2 way around the tire, flip the tire over and continue on the other side, it gets easier now, because you can hold the wheel with your foot while you pull on the tire to stretch it as you put it on the rim. Quickly straighten the tire on the rim. There should be a bead of glue between the tape on the tire and the rim. Remove masking tape.
5. Test your handiwork. Inflate to max. pressure. Try as hard as you can to roll the tire off the rim with your thumbs. The tire should not move at all and the tire tape should not come even slightly unglued from the rim. If this is so, go out and ride/race! If not, let it dry some more overnight and check in the morning. Hey, the masking tape works, doesn't it? No grabby brakes, no squeal.
Tips & Tricks:
1) Using Masking Tape to cover your braking surfaces on the rim before installing the tire. This will prevent the glue from getting all over the surface which then has to be carefully cleaned.
2) Vittoria Mastik One adhesive is well liked. While the 3M Fast-tak is known for it's extremely strong holding properties.
3) http://tirealert.com is a company which does repairs on tubular tires.
4) a Plumbers Flux brush is a good tool for spreading glue, however an old plastic bag will work in a pinch.
5) when you get to that last fifteen inches, fasten one side to the wheel with an old toestrap. Pull it up tight...like having three hands! Now you can stretch, curse, sweat and struggle with both hands, instead of one
6) Good options for old glue removal are bronze wool, stainless wool or a synthetic type pad. The maybe a bit more difficult to find than steel wool & are more expensive. Their benefit is that the missed residue does not leave the rust spots that steel wool can. A small brass brush could also be used.