The code 128 font is very extensible. I know that the COM DLL available below has been used successfully in Access. http://freebarcodefonts.dobsonsw.com/preview-code128-net-dll.html
It's easy to call from standard VBA, but I have not used VBA in Access. As far as I know it's no different, you essentially create a reference to it in your VBA project, and call that function from Access.
I found an article on that here:http://en.allexperts.com/q/Visual-Basic-1048/Call-dll-procedure-MS-1.htm
I'll give some thought to it and perhaps create an add in for Access in the not too distant future...
Thanks for bringing it up!