Renaming pin numbers is as simple as editing the number (edit->text) (just make sure the pin number is visible)Adding a pin is Layout->Pin and then walk through the options tab. If it's an electrical connection in the schematic then choose connect. If it's a non-electrical pin then choose mechanical.
You can also just copy an existing pin and rename its pin number afterwards. Very flexible.
Thanks for your response. To be honest I was looking for properties table etc. - over complicating!
The new pin shows up, but its text (pin number) is really big and shows up far away from the symbol. Why I can't just drag it to the right place and right click to select edit -> font I don't know!?!?
Hello Nigel and many thanks for your answer! I could never have guessed that was the way to do this.
Still, I can't figure out how to move the text closer to the pin (pad). Do you know how to do this as well?