A Software Pitch Bender for Yamaha PSS-290 Output

[prasadbrg]

Hello everyone!
I'm new to this forum, and this is my first post. I am not a pro, but there is this idea that has been lurking around in my head.
I have a Yamaha PSS-290, and I don't think it's a MIDI keyboard. I have a laptop running Linux. The PSS-290 doesn't have a pitch bender, and I desperately need one. I have Matlab installed, and know how to get things done in it (worked so far, at least). Here's the idea:
I create a piece of software (if it doesn't already exist) that takes the input from the keyboard, and has a pitch bender that I can manipulate using the touchpad's scroll feature. This is done in real time. End of idea .
I have a few questions.
1. Can this work, at least in principle?
2. Is there some program that functions as a soft pitchbender for realtime audio input?
3. Does anyone have any experience with the Matlab Real-Time Workshop?
4. I don't know how a pitch bender works, but I have a fair guess: The output pitch is a function of the input pitch and the bender position. What is the 'form' of this function?
5. Is there a better way of getting the pitch to bend, without (a) additional investment or (b) circuit bending?

The laptop has a Celeron 2.4 Ghz processor, 640mb of RAM, and an Acer M5451 PCI South Bridge Audio card. I have been able to sample the keyboard's sound with it.

I look forward to suggestions and comments. Thanks in advance!
- Guru