I found the most useful mode on the wipers is a single wipe; i.e. generally due to the screen size & type of weather a simple - push once for one wipe - is perfect to keep visibility clear;
This was the final circuit, double checked on RhoCar, Simon @ GBS and during build.
The switch over relay temporarily disconnects slow wipe from the park switch and over to 12v instead. A momentary push button to ground will energise the relay and wipe while pressed leaving the column stalk functionality to work as normal.
Red labels showing the wiper plug/socket lines,
Blue labels the relay connections.
Reference shot of the wiper motor plug before any changes...
...and the relatively simple loom insertion into the blue (12v) and green (slow wipe) lines. The trailing black line goes to the momentary switch to earth.
The relay will tuck securely next to the wiper motor.
Update -
My stalks didn't have an appropriate momentary switch, so I went for the Aux panel: a push button installed under the existing DRL & Fog light buttons in a position I can find with gloves on and without looking - so should be ideal.
Update - later
moved the switch onto the steering wheel.
Hindsight - Should have broken the white line instead of green, that would mean the flick wipe would not work when the stalk is fully off, and only work when the stalk was in the park position. Currently any time ignition is on the flick wipe button will activate the wipers - but only park if the stalk is one click up.
