It's been so darn long since I even turned on a pure DOS machine, I am not sure if the "telnet" utility is installed by default. If so, would it work to put :
telnet unix_server

at the bottom of the autoexec.bat scipt, or something similar?
Then, when you boot up, it will bring you directly into an interactive telnet sessions, but when you quit, it'll drop you back to DOS.

Am I making sense, or am I off my rocker?