One nice thing about 18F's is that you don't have to save W, BSR and STATUS when using High Priority Interrupts.
The hardware does it for you whenever an interrupt occurs by saving the values to "Shadow" registers.

At the end of the ISR just ...
 RETFIE FAST ; return from interrupt, restore shadows
and they all get restored.
A plain RETFIE does not.

When using Low Priority interrupts you do need to save them.
But they can be anywhere in RAM, just use MOVFF to save/restore them.