This isn't the "end-all-be-all" of figuring out how to set up the CONFIG fuses, but it's probably the best thing out there so far:
http://www.picbasic.co.uk/forum/showthread.php?t=543

As a lengthy string is likely to be generated, I assume a line continuation character is included in the scheme, can someone tell me what it is?
It's the underscore _ . The reference is a bit hidden in the manual, but it's there.

Could someone please explain what 'OSCS_OFF' means in either dialect. I don't see it noted in the available settings for the 18F4620.
It's not a valid setting for the '4620. You probably want IESO instead.
If you open up the P18F4620.INC file in \Microchip\MPASM Suite, you'll see all of the available config fuse options at the bottom of the file along with a fairly decent explanation of what they are. Of course, a better explanation is in the actual datasheet itself.
I usually take that whole chunk of information for whatever PIC I'm using, copy/paste it over to the 18F4620.INC file in the PBP directory and comment it out, then re-write the config register settings as I want them.

This is another recent post and self-fix somebody else had:
http://www.picbasic.co.uk/forum/showthread.php?t=9093