I was PM'ed a similar question about how to go about cold-setting, so here's what I wrote up. Note that it's primarily oriented to the Park tools one can get to do the job, but Randy's wood block method can easily replace a Park FFS1/2, and the string method replaces the FAG1:

First, you need a vice and soft aluminum vice jaws to hold the frame steady by the bottom bracket shell. Highly advise this, as you don't have to worry about any other mounting this way. Don't clamp directly to the vise - you'll do all sorts of damage to the BB shell - and use relatively soft aluminum if you're just using 90 degree stock as your jaws (not a bad idea).

A Park FFS1/2 can be used to pull the frame. Can be done by hand, but the FFS1 allows for more control, say, if you want to bend from the seatstay and pivot pressure below the brake bridge. Not a bad idea to do that on your Trek (or any bike with minimal visible brass or silver in the brake bridge). Yes, I've seen bridges split from the seatstay on older Treks because of this, though debates will go on forever whether this is a function of bad cold-setting or improper framebuilding. Doesn't matter; the takeaway is to be careful.

You then want the Park FAG1 (Frame Alignment Gauge) to make sure you've pulled an equal amount on each side. (The string method can replace this).

Also, if you have one, use one of the Park SBC1 spoke measuring tools to take periodic measurements between the drops; it's a handy tool in general and is a great measuring tool for this task. You'll wind up using it many times and you'll need it to check dropout spacing.

Last tool you'll need are a pair of FFG2's - the dropout alignment tool. After spreading the frame, the dropouts won't be parallel with each other. These tools measure that and will also give you the leverage to bend them square. (The threaded rod tools shown here can easily sub for these fairly expensive tools).

And, of course, heed the warning not to cold-set frames built with heat-treated steel tubing. Sure, you might be able to get away with it, but I wouldn't risk it. Too big a chance of cracking. Let the framebuilder get it right and then leave it alone.

-Kurt