gpio – Operating a key fob from a Raspberry Pi

I’m a relatively experienced programmer, but relatively new to raspberry pi, and definitely a lightweight when it comes to electronics.  So I have a question in that area.  If anyone can point me in the right direction, I’d really appreciate it.

I want to attach one of my car’s key fobs to a Pi and have the Pi activate the various buttons (lock, unlock, start, stop, and alarm).  Each of these buttons simply completes a circuit across two endpoints.  My plan is to solder jumper wires to each of these endpoints on the fob’s circuit board, then attach the jumpers to the GPIO and have the Pi complete the circuit rather than using the pushbuttons on the fob.

So my question is… is this something I could do directly with the GPIO or do I need to use a relay between the Pi and the fob?  And if it can be done thru GPIO, how?