Well that's a great shame, because I've been able to do it easily and cleanly in MuPAD for years, but I'd rather stick with Maple - I don't want to have to change my CAS.
Thanks for the reference to the paper.
I don't know about a CAS on a PDA, but for purely numerical software, you should have a look at LyME by Calerga:
It runs beautifully on my Palm Tungsten T3, and is really quite an amazing product. But it is a Matlab-type matrix oriented numerical package, rather than a Maple-type CAS.
There is also something called meditor:
but I don't know much about it, or whether the project is still active.
Some years ago the MuPAD people had a project to port MuPAD to the Sharp Zaurus, but unfortunately that project's stopped.