Modding a DBX 3BX to be a compressor?

[Darlington Pair]

So I ended up with a 3BX Expander (1st generation with wood sides) and it's been nice for transferring 4 track stuff to the computer and a few other things, it can actually be abused to sound kinda nice.

But, I got to thinking about all of the other DBX expanders from the same time period like the 117 that will compress and expand (the manual for my 117 has a mod for increasing compression.

Currently the 3BX is upward and downward expansion, has anybody around here figured out a mod to turn this into compression? A multiband DBX VCA compressor could be mighty handy!