This should get you started with the ADC part. No LM358 required.
http://www.rentron.com/PIC12C67XAD.htm

Then once you have the ADC reading the pot, take the number generated by the ADC and use that with the PWM output.

If you are using 8 bit the ADC will go from 0 - 255. Use a multiple of that number as the pulse.