I made a VST for the Sidblaster-USB:
I also built a SID object for Max / MSP, and made a variant for Max4Live (Ableton Live).
From version v.0.6 the AIASS for Max4Live consists of a set of different devices. Not only the Mono Synth, but also a poly variant and so-called "flow" devices that expand the polyphony of several SIDBlasters through overflow.
The AIASS for Max4Live is made by SID-object external, so you easyly can patch your own SID-Synth!
It is all free and open source (GNU GENERAL PUBLIC LICENSE)
see download section for downloads