The trick for getting the cables out of the splitter, is first remove the entire cable assembly from the bike .
With the cables removed, adjust the adjuster at the front end of the splitter all the way in .
Remove the threaded cap from the splitter .
Push the plug of plastic that the cables mount into, towards the front of the splitter, push the single cable from the handlebar up into the splitter, to get the swaged end of the cable free of the plastic plug .
You may have to hold the plug to prevent the cable from pushing the plug, and not have the swaged end come free of the plug itself .
Move the cable end off to the side, and get it completely 'disengaged' from the plug .
Now you can use the two cables that go to the carbs, to pull the plastic plug from the splitter body .
Now you can get the two 'lower' cables out of the plug .
Personally, I wouldn't get too crazy with grease in there, it just makes a mess of things, when you need to get in there again .
If you are unsure of how the cables are routed, mark the wiring harness, and whatever else the cables ride against with masking tape, so it isn't a guess where they went .