It turns out that one can leverage the Java capabilities of Matlab to conduct socket communication (without need for the Instrument Control Toolbox).
The above method of using Java currently only sends TCP messages. However, some clients (e.g., Rascal) may only receive UDP-type messages. A user-created toolbox provides this functionality via compiled MEX code:
My guess is that it would be better to try and modify the Java version to utilize UDP (so that no compilation and machine-dependent code is necessary). SUCCESS! See client_udp.m
Some Java links on UDP examples:
Some helpful references and commands
There's still the question of having any software work simultaneously as client (receive) and server (transmit), but it appears that at least one way communication should be relatively straightforward!