I don't have the TOC cover, but I would think it'd be easiest to use a little WD40 at the grommet and pull just one wire through first, then pull the other two.
When re-assembling, do just about the reverse. A little WD40, pull two wires through, then the last one.
Just be sure to add some sealant (and try to work it into the grommet a bit) when finished.
The instructions mention pulling all three wires through at once, with the new wires attached to the old ones. I'd think that'd be a little tougher.
If they say that because it's not too easy to get to the grommet from inside the cover, use some electric tape and tape the wire to a piece of coat hanger so you have something more solid that can be more easily directed to the grommet. But that's just my opinion. Do what you think best.
One other thing I noticed about the instructions, it says take the right cover off, but the stator cover is the left one? Atleast when I think of right & left of a bike, I think riders left & right.
AKA: Tim & 'The Adventure Cycle' VROC #24567, NEVROC, SteelCity VROC
"When life throws you curves,
Aim for the apex."