Yep, this is the info in the entitys file about decals:
;decals
decalmax = 1
decal0 = explosion416
The script
;Artificial Intelligence Script
; 0-once face player
; 1-once keep angle
; 2-loop face player
; 3-loop keep angle
; 4-once face up
; 5-loop face up
; 6-character-spot-decal (at end of entity characters gun if available)
;Header
desc = Runs Decal Loop
;Triggers
:state=0,plrdistwithin=60:rundecal=0,plraddhealth=-20,destroy
;End of Script
If anyone wants to have a go at recreating the conditions the decal im using is from the sprite pack 1 and the script has been posted above.
http://arenas4146.webs.com/