Why LCD won't work with RS connected to PortA.6 of 18F452?

[aratti]

Did you read the following notes on page 31 of the datasheet:

5: Bit 6 of PORTA, LATA, and TRISA are enabled in ECIO and RCIO Oscillator modes only. In all other
Oscillator modes, they are disabled and read ’0’.
6: Bit 6 of PORTA, LATA and TRISA are not available on all devices. When unimplemented, they are read ’0’.

Al.

[jellis00]

Thanks Al! That little bit of pertinent info is well hidden in the data sheet. The I/O section doesn't even mention this limitaton for pin PortA.6. Since my device has this pin I guess item 5: as you listed applies in my case.
Now I have to figure out how to set Oscillator ECIO or RCIO mode. I'm now trying to figure out how to set the configs to do this for the 18F452.