That's interesting that XC hasn't been opened up. Their stated plan was that they were going to open it up soon after they finalized the lang spec and that was right around the corner. That was a few years ago. I think the situation here is that nobody really cares so they haven't put any time into doing that.
I think that trying to kludge together some crap to half-ass get a dev environment for this on OS 4 is a complete waste of time. The audience who would find such a thing interesting is exceedingly small and they'll drop it at the tip of a hat the moment they try the official tool chain and development suite on a real computer. The XMOS tools for working with this family of micro controllers is first class, free and one of the highlights of utilizing these chips. The A1X1K motherboard has an XTAG port, right? If so, why on earth would anyone not use the excellent tools on a PC or Mac?