00 00 ... 04 00

Length = 16, but I just use 256 to be safe. There are 2 columns for every sprite except for MXXX.ARC files, which are something like 16 or 32 or something, I don't remember off the top of my head. Sprites are 4bpp reverse order while backgrounds are 8bpp. The title screen is 15bpp BGR if I remember correctly.

Position in a file varies based on size and type, so I usually just look for it manually. Some files have the palette position in a consistent spot, which can be found in Mir_Vimes' data in the data project tripod. In IMFXXX.IMG files, they're placed directly before the sprite sheets. When there's more than one sprite sheet in the IMF file, they're listed in sequential order as follows:

00 00 ... FF FF

The final palette in the IMF file is in the regular format. In every other file, it's usually placed directly after the sprite sheet. If you want to look at the actual IMF backgrounds (IMFXXX.TEX), the palette is located at the start of subfile X of the .IMG file. What I do is copy the entire subfile and paste it to the beginning of the .TEX so I can actually view it in tm. The only sucky parts about the .TEX files is they are split into layers and only have 2 columns, so if you want to rip them, you'll have to find some way to unscramble them and make them into one thing. Same with the other files, but those are much more manageable. 

I don't remember where palettes are located for the stage files, but I'm pretty sure they're placed before the sprite sheet. I do remember that they're 8bpp and 256 in length. 

I'll update this thread with more info as I find more of my notes.