Just open a text file, plainly type
JASC-PAL
0100
256
255 0 255
20 18 20
100 2 4
148 2 4
...
with a total of 256 colors (this here is the beginning of the Ken palette I just made for the previous example), save it as a .pal file, use pal2act right on it, then go for pcxclean.
I manually picked Ken's 15 colors from that specific sprite to make that palette, so I was sure Ken's color would be in the palette. PCXClean has zero tolerance.