Just type in during gameplay:

allen           radiation suit 
andrewbenson    invulnerability 
charlesjacobi   no clipping 
davidbrus       god mode 
deanhyers       strength 
digitalcafe     all map 
joelkoenigs     bootspork and "eat chex" 
kimhyers        position on map 
marybregi       invisibility 
mikekoenigs     all ammo 
scottholman     all ammo and keys 
sherrill        additional map info