Well, MyDMX does state XP or Vista, not Tablet. But there is an XP Tablet version, not sure about Vista.
Assuming that MyDMX would run on it, there's no real reason why using the stylus should make any difference.
I'd say if you get the opportunity, install myDMX on it and see for yourself. However, do have a clean install and fully updated. just make sure you have an available USB port and you should be OK. But again, it doesn't say "Tablet" for OS requirements, so you may be out of luck. Just trying to save you some potential frustration.
Some people are using MyDMX with a touch screen or touch panel. This is IDEAL for USER mode. And just like with that concept, assuming MyDMX works on a tablet, a stylus would also make an ideal input device for changing faders and quickly getting scenes selected. It's not really so much the "alternate controllers", it's more of compatibility with the OS or software.
My guess is that if the Tablet OS is XP or Vista-based, I'd say your chances are somewhat decent of it MyDMX working with the machine. But, don't take my work at "good as gold" as I can't say with any authority and I ain't about to spend money to test it. Just make sure you have a USB port for the dongle to plug into and that it has enough power on it to run the MyDMX dongle. Chances are you should be OK as far as that is concerned.