Inkscape requires a restart for loading the new palette.

Um, I did not have to restart to load the new palette. But I think I did it differently than you describe, aho. Knowing myself, I've probably done it the hard way, lol!
I opened GIMP, created the palette as I wanted it, and saved it in the GIMP. Then I copied it from....RATS!!

I can't remember exactly where I copied it from, but I think it was C: > Docs and Settings > Owner > .gimp 2.2 > palettes. All my custom palettes made in the GIMP are found here. I have to admit that I don't know why the custom made palettes are kept here, while all the other (pre-defined) palettes are kept in the Program Files directory. Seems to me they should all be in the same place. Anyway, I pasted it into C: > Program Files > Inkscape > share > palettes. And it was immediately available for use in Inkscape -- no restart of either Inkscape itself OR the computer!