Code:
attachmodel ( String modelname, String tagname, [Float scale], [String targetname], [Boolean detach_at_death], [Float removetime], [Float fadeintime], [Float fadeoutdelay], [Float fadetime], [Vector offset] )
attach a entity with modelname to this entity to tag called tagname.
scale - scale of attached entities
targetname - targetname for attached entities
detach_at_death - when entity dies, should this model be detached.
removetime - when the entity should be removed, if not specified, never.
fadeintime - time to fade the model in over.
fadeoutdelay - time to wait until we fade the attached model out
fadeoutspeed - time the model fades out over
offset - vector offset for the model from the specified tag
With offset being the missing key. Set this to player.forwardvector * 4 (or another number until you get it right).