Adding Headlamp Washers

[PaulDash]

The short:
I want to add option M288 "Headlamp washer" to my MY99 that was not equipped with them. Is this possible? What do I need?

The long version:
In a future project, after getting some mechanical stuff sorted, I will probably install Charles' projectors. The laws here state that Xenon lights must be self-leveling and have a cleaning system; the former would be very hard to install but is also hard to check; the latter is what I want to comply with.

My car is a MY99. It has the old-style lamps, no washers, no 7-liter fluid reservoir. I want to add the option M288 "Headlamp washer". What parts aside from the bigger reservoir, the triangles, and actual washers do I need? I already have the 4-stalk controller and the upper right-hand cap has an icon for the headlights, but do I need some extra wiring? A relay?

All help will be appreciated. I'd like to assess the budget and possibly get this done even before the Nine8six projectors, while the car is apart for other work.