Refer to project1999's setup guide found here:
http://www.project1999.org/forums/showthread.php?t=2651
These files must be changed:
arena.eqg
arena_EnvironmentEmitters.txt
lavastorm.eqg
nektulos.eqg
Nektulos_EnvironmentEmitters.txt
You'll also have to change spell files. It's all on the setup page.