As I have already mentioned in my previuos post, the use of SLC/SDA pins is mandatory only if your intention is to use the pic as a slave device.
Actually, I'd say it's mandatory if you intend to use the MSSP module (which can handle master- AND slavemode). But then, as Al says, you don't use I2CRead/Write as those are bit-banged and doesn't utilise the hardware and can therfor use "any" available pins - just as Al says.

/Henrik.