You don't need much to help. Obviously, a legal copy of EarthSiege 2 is nice. There should be various patch-levels and versions floating around; if you happen to be able to generate a SFV/MD5 file checksum list of the files on your CD-ROM, then please email it to marco@harddisk.is-a-geek.org.
For reverse engineering the bytecode format, all you need are the files themselves and the great hex editor HxD. If you can't calculate HEX in your head, getting a calculator with conversion WILL save you lots of work, but the normal Windows Calculator is also pretty sufficient. Sound and video files can be played back using VLC media player; images and textures have to be decoded as they're using a special color palette.
For reverse engineering or debugging the application binaries, you can use any x86 disassembler. There is one from the GNU project, MS Visual Studio brings one and of course there's IDA (which unfortunately costs a good chunk of money, but the freeware version of it is also sufficient).
RAM dumps can be obtained by HxD, though they are difficult to read. You're better off with single-step debugging.