The idea how to do it is:
1) set HD cache to higher quality (tune the settings)
2) render 1 frame from the middle of the animation with "save GI" checked on. A dump of the cache gets created on the disk
3) revert HD cache settings, uncheck save GI, check Load GI.
4) render the whole animation with this settings (and PT+HD as primary/secondary GI)
5) pray it works ;))
I know that is not user-friendly or optimal, interiror animations are currently the biggest unfinished issue of Corona. Hopefully I'll have time to look into it later.