My problem is this: I want to change my character's hairstyle (color is ok), but I have nGCD installed, and if I use "showracemenu" it assumes I'm starting a new game and I lose about 500 skill increases with the according pseudo-levels. So: can I change my hairstyle any other way? I'm not sure but I think the new style is one of the vanilla ones, if that's important. Or can I tell nGCD to lock my skill and attribute levels until I've done my changes?

Also: no, I don't want to use a wig for the rest of this game.

I imagine you could temporarily uninstall nGCD, change the hairstyle, then reinstall nGCD. NGCD ought to recalculate your character's stats correctly when it is reinstalled. But there might be some easier way to do it.

If you have Wyre Bash and the Construction Set installed, there's an easy way to do it...

Well, I don't know if this qualifies as "easier" in the eyes of most people, but I used Wrye Bash's "Details" function to find the FormID for the old hairstyle whose name I know, identified the new desired style's FormID from Oblivion.esm, found the place where the FormID for the hairstyle was stored in the .ess file by searching for the FormID, taking into account Microsoft's "little endian" storage rule (the least significant byte will be stored first, which means that a FormID of "a602d121" becomes "21 d1 02 a6" in the savegame file), and hex-edited the savegame file. Worked perfectly. Problem solved.

Microsoft's? https://en.wikipedia.org/wiki/Endianness#History.