There's several commands where there are so many lines of output that the first few will be pushed off the console and become inaccessible. I am looking for a command that'll allow me to read them.

Example: Help Invisibiliy 0 will only list the last few parts, mainly sound effects and the like. I know the MGEF for Invisibility is up there, it's just fallen off the console and I can't scroll up to read them.

How can I get to those lines?

What do you want? If its an invisibility toggle (what I think you want) TDetect toggles AI detection.

For other console commands they can be found http://elderscrolls.wikia.com/wiki/Console_Commands_%28Skyrim%29

BTW I dunno why you didnt ask the all knowing super answer machine that called google for Skyrim Console, the above link is the first listed.

Just use the page up and page down keys they should be above the arrow keys