I was able to run it after copying lisp.virtualmem to ~/il/medley and running medley without arguments.
It was interesting to try interlisp out :) The visible delay in rendering is annoying, but graphics is really great :D.
Hm. I can't seem to be able to load the memory file properly:
I load it with
./medley/medley/run-medley --vm-file lisp.virtualmem
Then I right click on desktop -> EXEC -> Intelisp
Open the INTERLISP Exec, but it doesn't contain any definitions, including the START-FIFTEEN function.
Am I doing something wrong?