Set up Android on the iPhone 3G will not be advisable for newcomers on account of a number of manipulations to be carried out. The entire tutorial on set up android on an iPhone edge
But for MAC owners, there is a much simpler solution!
It is a software called iPhoDroid, a download at the bottom of the page.
We’ll see how to proceed, but first this is what you need
IPhone 3G 3.1.2 (not 3.1.3)
Jailbroken with BlackRa1n, Pwnage Tool or Redsn0w (not Spirit)
OpenSSH installed and alpine as your password (you can change again after the manipulation)
Disable the automatic locking of the iPhone (Settings / General / Lock auto. / never)
Mac OSX 10.5 or 10.6
Good. Now install MacFuse if not already then download iPhoDroid. Ext
ract the archive and run the program.
Connect your iPhone and close iTunes. Then click on Run and wait a few minutes of installation. So there! OpeniBoot and Android are on your iPhone, ready to be launched!