I know this is very old news, but this worked for me:
In finder navigate to and select the files from the AVCHS stream you wan’t to batch import, right click and select ‘make alias’. Then drag these alias to folder you can navigate to with Avid and set those as the file location.
The advantage of doing this means the source file information will be correct, so if you need to do any conforming at a later stage, it should be pretty smooth (at least as far conforming can be).