It's possible to change the .dat files for the PS version as they are the same format as the PC version.
The PS files are in a different archive format (i.e. not .fs) and are uncompressed, so it's not currently possible to increase the size of files but it's possible to patch files with ones that are the same size or possibly smaller.
See:
http://forums.qhimm.com/index.php?topic=8130.msg99114#msg99114The offsets in that message are for the PAL version of FF8 but it's fairly easy to scan for the .dat files, I believe I just looked for the bytes 0B 00 00 00 adjacent to each other in FF8DISC1.IMG since most of the .dat files start with that.
Then you can find out where the section you want is by looking at:
http://wiki.qhimm.com/view/FF8/FileFormat_DATThen you just jump to the required offset from the start of the file - using the PC files as a reference would probably help make it easier.
It's fairly easy to recognize the right section because the monster info starts with an FF8 string which looks like ASCII (the monster name) followed by a bunch of 00s.
FF8 Strings look something like: Wos_jj - which is Squall and Elecjm - which is Angelo.