Hey guys, I've been lurking the board here for the last few months, and I figured out how to mount the A5A as a hard drive in OS X.
First, you need to get
MacFUSE = http://code.google.com/p/macfuse/
fuse-ext2 = http://sourceforge.net/projects/fuse-ext2/
Install both pieces of software. After installing fuse-ext2, do the following:
Navigate Finder to /System/Library/Filesystems/
Find "fuse-ext2.fs" and right click then choose "Show Package Contents"
Right click on "fuse-ext2.util" and open it with your preferred text editor
In your text editor, search for OPTIONS="auto_xattr,defer_permissions" and change it to read
Save and close the file.
Now on your Archos, go to USB Connection Mode and change it to the hard drive option.
It should now mount on your Mac as a usb hard drive, and allow you to copy files! No more USBNet!