Want to reuse "learning" remote control's IR LED

[corrado33]

So I have a learning remote control that doesn't work that well anymore.  I want to use the IR LED in it to act as an IR receiver, then use another IR led to act as a emitter.  Yep, you got it, I'm trying to build an IR range finder (more like an IR wall detector).  Anyone know anything about Learning remote control IR LEDs?

Yes I will eventually buy IR rangefinders for my bot, but for now, I have no money, and I want to see if I can figure this one out.

EDIT:  If you don't know what a learning remote control does... well, you push a learn button, then use another remote control to emit the frequency you want, then whatever button you tell the learning remote to use that frequency for, it will. 

[Razor Concepts]

Those LEDs are normal IR leds 

They can be configured to sense IR light - search for LED as a light sensor.

[corrado33]

Those LEDs are normal IR leds 

They can be configured to sense IR light - search for LED as a light sensor.

Yeah I've seen that done before, and in fact I was doing that a few seconds ago.  I saw this video...
LEDs as sensors!

and if you look in the description it says the leds are switched from forward bias (normal hookup i think), reverse bias (acts as capacitor) and discharging ()  I'm not sure what that last state is?  Is that when you'd measure the voltage?

[Razor Concepts]

I actually made it to a state science fair with this kind of stuff 
Basically, reverse voltage the LED for 1 microsecond, end the reverse voltage, and measure the voltage coming out of the LED(from its capacitance), and time the time it takes to reach a certain point. That time varies depending on the incoming light.

See:
http://www.merl.com/projects/LEDcomm/