I would like to know how to do this, too! If it matters, I have a Canon MX880 and I want to print from my Droid3.
Did find answer to my printer set up with Droid 3. Went to web site of manufacture & the easy to follow instructions were to go to "tools" on the printer, find set up network, it found my Droid3 put in the password I set up and it will now work wirelessly in the house off my phone. This may be your solution also. Good luck!
In Google Play, there was an app for Canon printers called "Canon Easy-Photo Print". I was able to print pictures and docs from my Droid3 immediately after installing it and recognizing my printer.
There is an app for HP called "HP ePrint Home & Biz". See if that supports your printer.