San Rensho 

I may (haven't decided yet) move up to late 20th century technology and go from a down tube friction shifting 6 spd to a 9spd. I just picked up a Shimano 105 triple groupo sans hubs for $50 and while most of it looks pretty pretty straighforward, I'm stumped on how to set up the brakes/shifters. I can't even figure out how to attach the levers to the bars!

Is there a good set of instructions somewhere online or in print on how to set it up?

What are possible pitfalls or things to look out for?

Thanks in advance.

HillRider

Go to Park Tools web site and hunt around in the tech pages. All you need is in there.

Retro Grouch 

#1 pitfall is rear dropout spacing. You'll need 130mm between your dropouts to make 9-speed work.
#2 you'll have to replace or at least rework your rear wheel.
#3 you'll need some downtube cable stops. Most LBS have a drawer full of them that they'll never use so it might even be a "gimme" if they like you. $15.00 if they don't.

barba

the bolt that tightens the levers onto the bar is under the hoods on the side. just pull the outside of the hood away and you will see the bolt head. it is really not all that difficult to install them. just be careful when cutting the shift housings. you don't want to leave them too short or too long, or the shifting will be really bad. on a similar note, the one tool you need (borrow if you can) is a decent pair of cable cutters.