Hi Sampsa,
MacTerm's Python interface isn't powerful enough to allow a graphics protocol to be implemented from a script. You can nonetheless find out more about the scripting interface from here: "
http://www.macterm.net/developer/quills/".
I am not that familiar with ReGIS or SIXEL but I am willing to consider adding support for them. The biggest thing I am lacking is a set of good examples because I have no way to test this feature. Would you be able to provide me with some examples [input text and the pictures they are supposed to produce]? Otherwise I can only rely on documentation (which I have already).
Also, this would take a significant amount of time. I imagine at least a couple of months, based on what I've read, though I would implement it in phases and some subset of it would be available sooner.
Kevin G.