Hi,
To me it looks like you're doing everything right though neither ANSEL nor CMCON should have any effect on GP3 operation.
However, I don't know the details on how meProg works. Is it possible that what it's actually programming into the chip is STILL what the code says - the default config for the 12F683 is MCLR enabled?

I guess you can always try that by changing the oscillator setting in meProg and program the chip, if it STILL runs then there's something going on with the CONFIG bits not being programmed to the settings showed in meProg.

I'm sorry for not having a definitive answer.

/Henrik.