Okay, you might want to check me on this. I don't have full errata...
According to TO, pg. 364, if I were to use VGLs on the transport config, I'd either have to have it land and fire off the grenades, or do a Bombing run to affect only one hex, all for 3 turns only as Light Smoke. On the other hand, if I were to fire off smoke SRMs from a 5-tube MML, I'd get (if I'm reading this right on pg. 371) the target hex and each adjacent hex covered in Heavy Smoke for 5 turns.
Could someone double check me on that?
EDIT: The LMGs are just for fending off infantry ambushes, mostly, not for assaulting infantry. Cal-Boeing is not responsible for death and/or dismemberment for chasing after enemy infantry with the Transport Configuration.