Try this site for some PSP tuts. Look for engraved button, same principles, just add color

http://www.pinoy7.com/psptutorials/default.htm
Or try this aqua tut http://www.zimmertech.com/tutorials_psp.html
This might work as well, maybe the best one yet

http://www.extenuation.net/psp/joestuts/aquacap.html