Lino! you gluing donuts! Dude you don't need a tool or anything, just make sure the contact cement is a little goopy and they slide on easy. What I like to do is glue both the donut and rim, let the rim dry and dunk it in acetone quickly and slide it in while the solvent has the glue nice and slippery. It also makes for better coverage imo.
Speed Merchant/Corally USA/Specialized RC/Team Kwik/Tekin/Sweep/Parma PSE/Team Pickles Performance