I think what you're looking for is in section '4.11 Pins ' of the PBP manual - specifically look at the table addressing pins on different PIC's... so if you're using an 18-pin PIC and your original example...

For CounterA=0 to 7
High CounterA
Pause 100
Low CounterA
Pause 100
Next CounterA

will sequentially toggle LED's across PortB.

Do a search in the MeLabs archives for "PICBASIC-L Using a variable to determine a Port pin - Melanie?" of 25 April 2003 wherein I gave a "Bouncing Ball" example... actually that whole thread is probably what you're after.

Melanie