SITL setup help

HI guys!

Long time no see =)

I’ve managed to compile the latest arduplane for pixhawk using this guide: http://ardupilot.org/dev/docs/building-px4-for-linux-with-make.html (Ubuntu in VM)

Then I’ve done this: http://ardupilot.org/dev/docs/sitl-with-xplane.html

Altogether with X-Plane 10 + MissionPlanner SITL works great.

And here is the question - I would like to modify the arduplane code and check it in the SITL. How do I do that and be sure that my code changes are compiler into SITL version? Also, where do I find the default .param file for the SITL plane?

Thanks a lot =)