well, extremely late response, but as I just put something like that together recently...
I have a G3 Powermac (under OS-9) with 2 TDM cards and an 882/20 interface running Pro Tools 5.1, great (and simple to setup) as an FX-unit.
With the Digidesign Adat Bridge interface it can be digitally integrated into any Scope system (I currently use the analog path).
Getting along with PT's project organization and edit mode may be a different story, tho

I started this 'project' out of curiosity because the cards were dead cheap, but I'm totally happy I did.
There are some modulation plugins (by Wavemechanics) that were directly ported from Eventide's 19" units (H3000/4000?) running on the same DSPs, and that sh*t rules.
I mostly appreciate it's a slightly different sound flavour from Scope or VST or iPad stuff.
The Powermac is running OS 9 btw...
cheers, Tom