According to this page
, the TMS1400 is a microcontroller in the same family as the TMS1000 (used in the Speak & Spell) and the TMS1100 (used in the Microvision). Dumping these is not trivial, but Lord Nightmare was working on it last I heard. Judge was also working on a CPU core. If these work out, expanding to the TMS1400 might not be too difficult, depending on how different they are.
I wasn't familiar with the Total Control 4, but found its Handheld Museum page
. It has cartridges, but they actually just physically control a switch on the system circuit board. So all that would need to be dumped is the TMS1400.
Personally, I would love to see dedicated handhelds like this emulated. There are lots of them out there, and they've pretty much been ignored so far.