With jailbreak of course.  I have not done this myself because from what I read you need iOS4 and I really do not want to put that on my iphone 3g.  But, for those of you that already took the plunge, AND have jailbroken AND care enough to want to bother in the first place… Here you go.

The video will be at the bottom of the post..

David Romhan Torres: “I just make iMovie for iphone 4 run on an iphone 3GS, it’s very simple just download it from iTunes, modify info.plist file and change the Minimum system version to 3.0.0 and front-facing-camera to false.”

Really, it just does not get easier then that. Now I have read mixed results from people both on iOS4 and a few who did it on 3.1.3.  I also read that you can grab it from Installous.app (free app from Cydia) and it will install it for you.  I’m checking into it now…  Will update when I know more.