2 is the device number of my soundcard's native ASIO driver, 0 and 1 are the MME and WDM ASIO drivers. As far as I can tell, PD does not set this number from the command line, so at the moment you must change it and recompile.
Alternatively (like if you don't have a compiler ;-) rename the ASIO entries in the registry (backup first) so that the prefered device becomes the first on the list. (The devices are sorted alphabeticly). It is at HKEY_LOCAL_MACHINE\SOFTWARE\ASIO
Remember to restore the names if you upgrade you ASIO drivers for some reason :-)
Cheers Soeren