To be honest, you don't really need one, with one very important caveat. It works perfectly well without using TARGET at all....except you cannot use buttons 1-19 on the throttle independantly of the stick, and vice versa, as the game can only see the one device. Which is to be fixed soon as far as I know. This pretty much limits you to the buttons and metal switches on the control base.
The way around this is to create a virtual stick in TARGET that allows all 32 buttons to be used. I haven't actually bothered having a go at this yet but it is very easy to do from what I have see. Just select both devices in the profile you create, select a button on the stick, select a key on the keyboard for it to press and that's one button done!
As far as I know you don't even need to worry about which key you assign to the which button. If you already have a good idea of which switches and buttons you wish to use in-game, then you can assign any old key to those buttons, even just selecting `....=, q..],a...# and \.../. It may look like nonsense but when you configure the keys in game you are using the buttons and not the key presses they issue.