Unfortunately, to communicate with an SCXI chassis via Serial port on the Macintosh would require that a driver for the SCXI 1200 and SCXI 2000 chassis be written. To write such a driver would not only require register level programming, but a thorough understanding of the SCXI hardware, some of which information might not be available in manuals and such. Because of this I don't think it would be feasible to use the SCXI 2000 chassis on a Mac.
I tried to think of other approaches, but the only alternatives I could think of were to use a Windows Machine with the SCXI 2000 or to put one Mac near the equipment, as you mentioned previously.