I have just had a look at the 1100P wiring diagram, and the headlight wiring doesnt go any where near the right switch block, so wiring in one of the switches to control the lights wont be an easy job.
It could be done, but it would mean stripping the bike to get at the wiring to replace/ modify the circuit.
To do it properly, you would need to get the proper crimping tools for the pins used in the relays and source the pins.
In the normal bike, power goes from the fuse box ( Fuse C) to the normaly closed contacts on the start button, to the Hi/Lo relays, and the hi lo switch to enable the selected relay . On some variants, the headlight wiring doesnt go to the start switch but directly to the relays and HiLo switch.
P.S. some might find that the high beam flash switch doesnt work. That is because the flasher switch has been used as the radio transmit switch.