The Purple Cat Tools table files aren't complicated. The tables for version 0.3 are just lists of [filename],[location in ISO]. For instance, let's look at the entry for file 0001:
0001.boot.cfg,0x000A7000
That tells us that the file is named "0001.boot.cfg", and it starts at byte 0x000A7000 in an ISO image of the game disc. The passage prizvel quotes above explains how to derive the 0x000A7000 from the disc's TOC, and where to find the TOC in a disc image. Creating a new disc table just requires a hex editor to view the TOC, a calculator that understands hex, and a lot of patience. (I seem to remember that utunnels once managed to dump a disc for an entirely different Squaresoft PSX game using Purple Cat Tools and a custom table, a very long time ago.)
Version 0.4 of Purple Cat Tools doesn't even require the addresses, just a list of filenames, but I never really finished it, so some of the scripts are buggy.