64-bit CDB

Hi, I've written a Python implementation of the CDB algorithm as part of 
a project. I'd like to convert it to use 64-bit disk offsets to get 
around the 4-GB limit, but I don't understand how the 
hash-to-disk-offset lookup process works and what depends on 32-bit-ness 
well enough to do it with confidence.

Has anyone done this already or can anyone point out what I'd need to 
change in the algorithm to get it to work?

Thanks very much!

Matt