Well, it might be possible if he uses GHDL (
http://ghdl.free.fr/) because
it's a VHDL frontend for gcc, but it's not likely that he could use it
with a Delphi program.
This page talks about starting a simulation from a C program:
http://ghdl.free.fr/ghdl/Starting-a-simulation-from-a-foreign-program.html
BTW: GHDL is working very nicely these days and it even runs on my Mac.
I've been using the latest version (0.16) for the past few weeks and I
haven't run into any problems with it. It's good to have an open-source
VHDL compiler/simulator that actually works.