it wouldn't kill you if you search a little bit...

http://forum.scummvm.org/viewtopic.php?t=9009

It's nothing complicated. First, go to this webpage. There are 4 versions. Since your HTC Desire has no camera button, i recommend the alt-tremor version (or alt-vorbis, i personally didn't try it yet). Then download scummvm.zip, and extract it in the ROOT of your memory card so that you have folder...