i guess that if you have EVERY users' printer installed on the server, too, AND can associate a given user with their printer, you can print directly from the server, giving your users a page saying, "go to your printer, now".
to be honest, it would be a million times simpler if you just showed them a page saying, "click here to download the image, then press 'print'".
if you are not allowed to deviate from tif, then there is very little else you can do, as far as i can see.
let's face it, if you tell them to press "print", it's not your fault if they don't know where their own printer is. if you send to the printers directly, then all your users will hold you entirely responsible for finding everything they ever print.