Using simulavr and avr-gdb with the Arduino

Hi, so doing that NTSC thing an not having a soft reset Diecimila I realized it would be great to be able to test code without using the Arduino (it was far away when I needed to reset it). I had installed OSX-AVR anyway to use the USBTiny so simulavr came with it (why is it not in the Macports?). I modified the Makefile (0007) to generate a .bin to load up in simulavr and got simulavr-disp loaded in X11 (pretty darn sweet if you ask me!). Now I connected using gdb... but I'm not really sure what to do from there on. Any one has pointers here? All I'm looking for something like setting break points and stepping through. I know this is a little out of the scope of the Arduino project, but since some of you guys know uC's very well I figured I might ask here.