The programming works for my 318i... maybe the prior owner did this mod:
e36_euro_wiper_control_module
Edit: here is a place in the states that sells that module...
LeatherZ: Intermittent Programmable Wiper Module
to program:
with the car running; switch the wiper from off to intermittent _briefly_ and then turn it back off... wait XX seconds where XX = the number of seconds you want between cycles... (ex: leave it off again for 5 seconds)... then turn it back to the intermittent setting again and enjoy 5 second intermittent wipers.
Note: every time the car is turned off; the time resets to the default (8 seconds I think)...