Here's a start:
- Open the units.gif in PSP
- Go to Colors > Edit Palette...
- The first color on the second row is the foreground color for the window title. Change it to a unique color (not yet anywhere else in the palette, this ISN'T yet the color you want to use finally)...
- Now change the first of the block of black colors at the bottom of the palette (index 192) to color (135, 135, 135). That's what used to be that foreground title color.
- Use the Color Replacer to swap these two colors (that is, swap the color at palette index 16, with the one at index 192). Your units will now look normal again (after looking funky when you changed the first palette color).
- Now open the Palette Editor again and change index 16 (first on the second row) to your desired title color.
Now have a look at what Civ2 looks like...
- To match the color swap, you need to make the same changes to all the other gif's as well though, since the other graphics "borrow" their colors

eek: actually, only the first 192 colors of the palette... nevermind) from the units.gif file.
The same method could be used for changing the "shade" color (i.e. the black backdrop of the titles), which use the very first color in the palette... The problem is, that color is used by a lot of other things as well (like the black background on the main map, and the color of unexplored squares on the little world map).
In short, it is quite possible, but the benefits might not outweigh the drawbacks and trouble to get there.