...into the official campaign? I have downloaded Lupin III's Armor Pack and All Arrow Types, but I haven't been able to locate any info on importing them.

Help?

You can import them, using the toolset.
Haven't tried it myself yet, though.

Let me rephrase: How do you unlock the official campaign so that you can use the toolset to import .erf files?

Any areas you have completed become .mod files that you can access via the toolset. For areas you haven't yet completed change their file type from .nwn to .mod. Now you can access them. This means you can see eveything in those areas so mind you don't spoil yourself! ;)