If you've looked at the S-M site, you may have noticed at that the bottom of an item display you'll see several tabs, sometimes one is 'Instructions'. There's one on the sampler pack page, and it covers the finishing papers and wet-sanding. You better believe I read every word, and found this:
Most professionals prefer mineral spirits or naphtha for wet-sanding lacquer finishes, and use water for synthetic polyurethanes and esters. Water can be used with caution when wet-sanding lacquer, but be very careful near exposed unfinished wood surfaces such as F-holes, volume and tone control holes, screw holes, neck pockets and routed pickup cavities. If water penetrates bare wood, splitting and lifting of adjacent lacquer can result; nor should exposed wood be soaked with mineral spirits or naphtha, although these lubricants are more forgiving.which I found very interesting. Because I was nervous about using wet sandpaper on that instrument to start with. However, this being a lacquer finish, I had the mineral spirits option, and I had some. So I stuck a piece in some spirits this morning to soak and about half an hour ago I took the guitar down and did the sanding. And that was easy.
There were only a few patches that weren't smooth, so I'd pull the folded paper out, shake it to get rid of excess, and gently work it over a surface, dip and shake once or twice to keep the paper wet(in the wind the spirits evaporate fast), then wipe it off with a soft cloth. The whole surface is smooth as silk. Right now it's hanging back up; I'm going to let it sit for a while to make sure all traces of the mineral spirits are gone, and then I'll shoot the finishing coat.
This is the one I used, by the way.