I used push to make switches and a small plastic case from Maplins. The green button is up. The cable was from an old fax machine ( has to be RJ12, 6 pins).
I chopped off the BT plug and wired to the switches as per Nexstar Resource site instructions, then plugged it into the guide port.
It works like a dream. The lead is long enough so that I can have the controller right by my laptop, so for planetery imaging at the 1x speed it's perfect.
