The Position Hair works great on the ornatrix hair, but when I need to cache everything out as Ox alembic, the Position Hair doesn't let you select the ox alembic. is there a work around for this?
You will have to cache them separately.
Oh sorry, I misunderstood the question.
Position Hair needs to select the uncached hair object to read the necessary internal hair data.
Ox alembic doesn't expose the necessary interface that tyFlow needs to read, so I don't think it will be possible, no.