Empower SLA and Eidolon Breath Weapon

[Kazarin]

Is it possible to use the Empower SLA feat to increase the power of the eidolon breath weapon?

Empower SLA states that: "The creature can only select a spell-like ability duplicating a spell with a level less than or equal to 1/2 its caster level (round down) – 2."

While fire breath is a level 2 spell, there does not seem to be an equivalent spell for ice, electricity and acid (admittedly I only did a cursory look). Is this only available to fire breath? Additionally, how would caster level be determined? The magic sla evolutions specifically provided the caster level formula but it is noticeably absent for the breath weapon. Thus, would you go by the level minimum (summoner level 9 to even get the evolution)or HD or HD-2 as used in the various magic sla evolutions in determining when the breath weapon qualifies for Empower SLA?

[concerro]

Breath Weapon is an SU(supernatural ability), not an SLA so you can not use empower SLA to improve upon it.

edit: If you are not asking about the eidolon evolution then I am confused, and would need a book as a reference.