I would think it should be relatively easy as long as there is room for more output channels. If my understanding of how the gauges work, once you have an output channel, you can make a gauge for it. I could be completely wrong, of course.
Robert '95 Ford E150, 300 cid six. MS1. Custom MSnS-Extra '92 Winnebago Elante, Ford 460 cid V8. MS1. Custom MSnS-Extra '93 Bayliner 3288, twin Ford 351 cid Windsors. Converted to tuned port EFI. MS1. Custom MSnS-Extra '95 Dodge 2500 4x4 488 cid V10. MS3, work in progress