Or you could try one of these: http://www.tinytachuk.com/
I went for the comercial version which can be used on any engine type, 2 or 4 stroke, 1 to 8 cylinders. It costs £45 inc del.vat - £10 more than the standard version.
Ordered one myself last week and the guy sent one out with an invoice. You can then send him a cheque as payment. I've attached mine using cable ties, has it's own power supply so only took 5 mins and easily removeable - Seems to work well
*I have no connection with the company, just impressed with the service