I think what your talking about here are Celtiberians, there are several sets available from Hät and Orion(which I thought quite good)that have figures that would be suitable to represent a Lusitanian force, in particular those with small round shields daggers and sinew helmets, as many were apparantly light troops though some armour was in use...

There is a new English version of "Armas de la antigua Iberia" in the works though it seems to be taking some time to be published...

http://www.pen-and-sword.co.uk/Arms-and-Armour-of-Ancient-Iberia-Hardback/p/9786

The sets that would provide suitable troops for this war are;

Orion Iberian Infantry

HaT Spanish Cavalry

HaT Hannibal's Cathaginians - Spanish Infantry

Hat Carthaginian Allies (only two Iberians)

Odemars Iberian Infantry (the quality of this set seems pretty low)

In a pinch you could probably use some Celts as well.

If only HaT would bring out their 1/32 Celtiberians in 1/72...