OMG u rock ive been looking for this for a long time.
Another Good app is Math Tablet from Statsnow, add the XCAS module and you get a full functioned CAS system (XCAS is used in the HP-49G+ calculators.)
Finally one way which I have gotten actual MATLAB to work on the axim is by using pDosBox, especially the 2.0 Beta. Use Matlab 3.0 as it is freely available on the internet. The only thing that sucks about this is that it is a "students" version and thus severly crippled.
I would KILL for a fully Matlab compatible clone on the PPC.
EDIT - oops I just read your entire post, yeah Matlab 3.0 sucks