Sorry if this is already known! Couldn't find any information about it.
I've recently seen frozenspade walking to the side of the cliff before talking to the head after exiting the catacombs. While experimenting with that, I saw something interesting: if you walk to the spot where the road that goes down to the ghost ship starts, Guybrush doesn't put the head away before talking to it. However, he doesn't put it away after talking to it either. You actually have to walk to a different place and use the head so Guybrush puts it away, which loses time.
The good thing is that it works both ways. So, when exiting the catacombs, immediately click on the side of the cliff and wait for the animation of Guybrush putting the head away. Now walk to the place where the path going down starts and talk to the head. Guybrush will talk to the head without pulling it out! If done correctly, this saves almost as much (maybe as much if done perfectly) as the "traditional" frame-perfect head skip, and it's about 20 times easier. Here's a video showing the skip in action.
If you don't manage to click on the side of the cliff in time for Guybrush to walk there before the default animation takes place, you can still walk to the place where the path going down starts and talk to the head; it still saves time. You can also go for the traditional frame-perfect head skip and use this one as a backup if you miss the frame-perfect one (and you most likely will :D). Even if you mess up some of the steps (as I have, many times), chances are it'll still be faster than playing this sequence as intended.
A hint about cursor positioning: you can move the cursor outside the game window while the conversation starts, use whatever visual reference you have on your desktop to know where you should position the cursor, and enter the game window again. ScummVM has a shortcut to trap/untrap the mouse in the game window; by default, it's Ctrl+m, but you can rebind it to any key using ScummVM global options.
Just noticed that there seems to be a faster (and harder) version. It requires the same frame-perfect input as talking to the head, but, instead of talking to the head, you use it so Guybrush puts it away. This is faster (but just as hard) than talking to the head because, when talking to the head, the animation where Guybrush puts the head away after talking to it is one second longer.
Here's a video showing this faster skip in action. Good luck using it in a run!
If you go for the faster version of the skip and you miss it (which is very likely), in the floppy disk versions you'll get stuck in the middle of a "Use" action. The fastest way I've found to deal with this is to hold "4" to use the skull and the walk to the side of the cliff.
Here's a video showing the backup plan. Note that the backup plan is slower than not going for the faster skip at all, so use at your own risk!