There should be a better writeup on the PH site. Search for elkinsteon.exe. elkinsteon.exe is what sets the relationship between an Insteon address and a 1-190 number Elk uses.
Basically, use PH to configure everything with the Insteon links. Configure the lights/devices in ElkRP as "serial expander", using slots 1-190, they don't have to be consecutive. Run elkinsteon.exe and assign the 1-190 ElkRP number to each light/device. Connect PH to the M1 XSP and send the data. Reconnect the XSP to the M1 and test.