How do I update mpguino firmware? No USB port on MPGuino..
 

I have this version:
http://opengauge.org/mpguino/guino1.JPG
What needs to be done to physically wire it to the computer so that I can make firmware changes and upgrades?

I guess this must be a super-difficult question to answer.. :/

What you expect that a firmware change does? When did you bought it?
You might wanna take a look at code version history. MPGuino - EcoModder Roll down the page.
But yea, all you need is a AVR(or Arduino..) programmer, and connect it to that. Maybe it has a 6-pin header somewhere?
And lightest/fastest software for this is in my opinion Arduino IDE.

Probably the easiest thing to do is pull the chip off the board and stick it in another arduino board for programming. Otherwise you'll have to wire up some pins or a connector that will connect up to a FTDI board so you can hook it up to the computer.

Did'nt thought of that, yea that's the easiest. You win :-P