Can I boot Android on the LG Arena KM 900?
You've already found the forum for the main project to port Android to the LG KM900 at http://androidarena.pytalhost.net/

All of their effort towards porting Android to the KM900 is being tracked on this Google Code page http://code.google.com/p/arenoid/ their project status page doesn't look like they've managed this yet http://code.google.com/p/arenoid/wiki/ProjectStatus

So, unfortunately it doesn't look like this is possible yet. I think that your best bet to speed up the process will be to visit that forum and Google Code section and volunteer to help them out in their efforts.