Fitting a Vapor Dash

Got one of those fancy Vapor dashes for a steal so thought I'd put it on the RD. All I want is the tacho and temp gauge to work. It's a royal pain in the arse trying to get the speedo to work, so that's out!

I can either wrap one of the input leads for the tacho around one of the plug leads, or connect it to the input side of the coil. Wrapping it around the plug lead sounds like a crap idea, so I tried plugging it into what I think is the input side of the coil. Bloody thing doesn't work.

Any ideas?