Tim,
It makes no difference whether the the GL is Direct fire or indirect fire. Direct Templates (Shotguns, Flamethrowers, et al) may not be Aimed as there is no To Hit Roll*; in actuality, there is no bonus to be gained from the Aim Action, as Direct Templates' DM is unaffected by To Hit Rolls*, therefore, the Action is not necessary.
Ranged Templates (GL, RL's, et al) use a To Hit Roll, and may be aimed.
* - In an environment that could produce a Weapon Malfunction, a "To Hit Roll" is made to determine whether the weapon malfunctions; this roll, still, does not affect the DM of the weapon - it only determines whether the weapon may be used on that Action, and whether a subsequent Action is needed to "clear" the weapon.