Items:
lightType = NoLight, ConstantLight, or PulsingLight;
lightColor = rgba between 0 and 1;
lightTime = time in ms; (Probably for pulsing)
lightRadius = distance;
lightOnlyStatic = 1 or 0; (Means lights will only be on non-thrown items)
Images:
lightType = NoLight, ConstantLight, PulsingLight, or WeaponFireLight;
lightColor = rgba between 0 and 1;
lightTime = time in ms; (Probably for pulsing/WeaponFireLight)
lightRadius = distance;
Again, I think these will show up at the mountpoint, and these settings are for datablocks.
You could probably attach a real light to an item, but as for attaching to an image, it would have to be a left hand item and you would attach it like you would for doing /light