Pour the hot water into a measuring cup and put the knife in it.
Shake the knife in the sink to drain, then cut the cream cheese.
Put the knife into the measuring cup again, and shake lightly to drain. Even if a little cream cheese is stuck to the knife, it will come off and you'll have a clean cut. Repeat.
Addendum: User "Repipaku" tried it with butter and it worked. I tried it with butter, too.
Addendum: User "Oyuki" tried this trick with Camembert cheese!
Story Behind this Recipe
I cut cake this way, and thought it might work well with cream cheese. When cutting cake, I wipe the knife with a paper towel after each cut. My fruit knife is the same size as my measuring cup, so it is convenient.
You can use a knife if there is a container, such as a flat metal tray, that is large enough for the blade to submerge. Use water heated to 90ºC. Be careful not to burn yourself.