Chris,
Edit: I have just realized that Robin had already mentioned the Shoestring adapter. Anyway, I will leave my post
As far as I can remember correctly, SS2K has a completely different pin layout than the standard ST-4. I have seen some discussions, I think on Cloudy Nights, about it. There is something tricky about that wiring, otherwise Shoestring Astronomy wouldn't sell the guide port converter:
http://www.store.shoestringastronomy.com/gpcnv_ss2k.htm
I use Borg 50mm and Orion SSAG with Vixen SXW and it works under light polluted sky in my place (Waitara, NSW). But Vixen SXW's pin layout is compatible with ST-4. Well almost, becaus RA+ is mapped to RA-, Dec+ is mapped to Dec-, and so on but software can handle it.
Regards,
Matt