My method of TIM construction. Also known as Oh MY GOD! more hex editing.
Example is a 2 palette RE1 TIM file (Cut out of the EMD)The header is always the first two rows (0-13hex). The header is always slightly different depending on if it is an 8bit, 16 bit TIM and depending on how many Sections the TIM has.
Appendix: RE1 can't use 16bit tim files. RE2 Can under windows 98, under XP it has hissy fits. Never tried 16bit tims on RE3. Each pallete is always 200Hex and the first one starts at 214hex (the 2nd would be 414hex, 3rd would be 614 and so forth).
The resolution is 12hex long. it may not necesarrily be to do with the resolution but its always different on different sized TIM Files.
The image data is the pixel by pixel colourisation. Runs to the end of file (except in PLDs/RE1 EMDs, watch out for their pointers).
If you plan to put together 2+ palette TIMs make sure one of the TIMs you make has all three sections in the image, with the other two sections loaded so they use the firsts pallette
NOTE: They need to be loaded with the Pallette index kept intact, this will make the other sections the wrong colours but the game will correct it. You also make TIM files for the individual Pallettes for the other sections.
E.G:

With the example I made Steve's body section use the heads palette (bottom image). Don't worry if it looks wierd. Just remember colour 1 on one palette will be a different colour on another.You need one TIM to be a complete image to use as the donar image data as well as a palette donar You also need other TIMs made as the palette donars for the other parts.
Break Down:
Tools Needed: Hex Editor, Whatever to TIM converter, BRAIN.
1) Make 1 TIM with all Sections (With all sections loaded to use one palette preserving Palette index)
2) Make other TIM files for the other sections so you got Palettes for them.
3) Cut out from an original Capcom tim the palettes. Then paste in order from left to right your custom made TIM Palettes.
4) Cut out the original image data after the resolution header. Then Cut and paste across yours from your complete TIM.
5) Save and you are done.
Note: Remember to use the original TIM for the model. It saves complications laterIts not much more complicated to do the tim editing within a PLD for RE2/3 or EMD for RE1, Just remember in those you can't cut right to the end of file as at the end they have important Pointers.
Makes Sense? YES/NO?