Mythic tier on an animal companion

[wdmartin]

My player is going into the final battle of her campaign, and has informed me that she plans to cast the spell Ascension in order give a mythic tier to her animal companion.

This appears to be legit rules-wise -- he's technically not a mythic creature himself, even though his mistress is.

But I don't see any way to add a mythic tier to him in Hero Lab. His configuration screen lacks the "Mythic character" checkbox because he's an animal companion.

Is there any way to give him the Mythic tab, or am I stuck doing a bunch of adjustments and tracking his mythic power/etc manually?