I have an old Sega mega-drive and I want to make it so the controls are wireless.

True is I have no idea were to even start to send the signal from the 9 different wires that make up the output wire of the controller and send it wirelessly to a receiver what can do the opposite again and input it into the console.

Can anyone help me in the right direction?

 

all depends on the controls you/it are using..
If its analog then you would probably convert that to a digital signal then the receiver would then have to turn that back into analog..
You will more than likely require some microcontrollers/circuit boards/components and have to write code.. Are you up to that?

Are you aware that wireless controllers already exist and are cheap for that device?
You will spend quite a bit of time/money on this if you want to do it yourself.. far more than it would cost to just buy off the shelf..

 

http://nfggames.com/grafx/MD6bottan.png

looks like its straight high/low clock pulses, with timing, if this is the controller, difficult to do...

 

Maybe you could start with using something like the XBee modules.