Here's a pretty cool program for transcoding AVCHD to Mpeg2 for editing:

http://vasst.com/product.aspx?id=bf3e2d5a-7c2e-4969-a8dd-7cee2cefba30

The transcoded files should work with any NLE, even FCP, though you'll have to do the transcoding on either a Windows Machine or a Mac with Parallels or Bootcamp since it is a Windows only program.

I just bought it last week and it works well with Sony Vegas.