how would one make an oscillating voltage divider? like an automated pot ?

[Derringer]

so for instance, say you wanted to build a wah circuit but without the foot control

you could just set the speed of the voltage divider to go wah wah wah wah wah wah wah when the effect is engaged

I imagine you'd need two out of phase LEDs.

like the idea proposed here
http://www.diystompboxes.com/smfforum/index.php?topic=78620.0

How to do this?

[Processaurus]

http://www.geocities.com/thetonegod/rockncontrol/rock.html

That's the literal approach for making a DIY voltage controlled pot, to make a wah wah that is voltage controlled there are plenty of voltage controlled filters out there in synth land (VCF's), many of the stompbox incarnations envelope filters, but could respond to any control voltage you wanted.