On Linux there is zTelnet so I hoped that something similar exists for Mint.
Have you tried grabbing the source and compiling it for mint?Maybe someone with a FAST cross-compiler setup (Atari Running On Any Machine) would be willing to give it a try?
There's a shot that some such unix client would compile.I've never been a programmer...but it would seem to me that such a client is likely just gnu telnet with some calls to already existing sz/rz object modules. If you've all the needed libraries installed, and the make file points to them correctly...it just might compile with few to no changes in code.
Brian