[PlasmaKrab]

As with ATRL/RPG/LAW-type thingies, you can add values to the HE parameters of the weapon, then give HE ammo to the missile team/vehicle. As a rule, HEAT rounds will not be used against soft targets in the game.
The Khrizantema and other Russian missiles can give you stock ratings for FAE warheads, for basic HE-Frag warheads look at equivalent HE LAWs in some OOBs, or deduce from artillery rockets or mortar rounds of similar caliber.