Take a look at the:

    http://www.qsl.net/n5tle/

This link describes a DMX512 dimmer reciever. The output is a set of
analog voltages proportional to the recieved value (such as would be
input to a dimmer pack). This project seems to solve the first part of
your request.

Next, try:

    http://www.mindspring.com/~jlittle/picstuff.html

This describes a MIDI controlled lamp dimmer. From what is presented on
the page, much of this project is untested. However, it would be a
starting point for building a PIC based dimmer.

It would seem that by merging the two projects you could build a DMX
dimmer.

This is something I've wanted to do, but have never been able to find
the time for. If you do something, I'd be interested in hearing about
it.

Good Luck,

Roy

--
Roy Turner                      Email: rturner@fa.disney.com
Walt Disney Feature Animation   Phone: (818) 526-3334
500 S. Buena Vista St.
Burbank, CA 91521-8950