Shouldn't be hard if your already using a pic...
An IR transmitter led should be connected to the transmitter pic
And a standard 38Khz ir decoder (like the ones used in modern TV, video,...) to the receiver pic. The transmitter led should be buffered with a transistor.
the output of the ir decoder is always high when no signal is received. As long as you flash the transmitter led at 38Khz (approx., doesn't have to be perfect 38khz), the decoder will output low.
use timing to create binairy codes. For example 1ms on is a logic 1, 0.5ms on is a logic 0, ...