I have been playing with th Tiny Giant. It sounds great through my Marshall cab. For fun, I put it through an old car speaker, and also through my old stereo speaker. It has an interesting sound - crunchy. It's a cool effect, but not for all styles.
I was wondering if a cab simulator would modify the sound to make it sound better through non cabinet speakers. As I understand it, the cab sims (condor for example), are designed to go to a mixer without an amp.
If it's any kind of decent car speaker, it's designed to have a very flat frequency response, as opposed to a guitar speaker which generally has a boost in the upper mids then a high frequency rolloff. My opinion is it will sound kind of boring or too bright (fizzy) unless, perhaps you can push it to breakup.
I don't know how to make a modeler circuit, but behringer makes everything cheap, like a Vamp or some such. Probably pick one up for $10.
CHAD