Voltage-to-resistance converter for using any joysticks

[ConKbot of Doom]

On maxim/dallas semiconductors website, in one of the app notes, they posted a design for a simple voltage to resistance converter, that doesnt use a pic or other microprocessor like what would normally be used.
http://www.maxim-ic.com/appnotes.cfm...te_number/3284

I think that that would suit our needs pretty well, and maxim stocks a 8-bit up/down digi-pot, the max 5455 http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2568 would work, and sparkfun electronics had a cheap breakout board so you can avoid having to make your own board for the tssop 14 package. http://www.sparkfun.com/commerce/pro...roducts_id=498

that would allow us to input an analog voltage from whatever source we want.

I would imagine that you could possibly come up with something using an op-amp and a few FETs to convert voltage to resistance also.

Any thoughts to the legality of this? I don't think they could have an issue with this, like they would have with putting a PIC or other micro controller into a joystick.