Rob,
Let's start at the beginning.
Are you sure it is frozen?
Tap the surface with a straw or a plastic spoon handle.
They often look frozen when they are low on water or just old. They can also form skim ice the cells the same way sea water freezes at the top by pushing the salt down.
If it is, and it is a typical automotive battery, it is probably toast. It should have retained the charge from last month's drive. If you left something on and killed it so dead that if froze, then yes, it will be good for a core deposit.
If it is not really frozen, get an extension cord and put it outside to charge it. Make up the water level with at least de-ionized water if not distilled and then try charging it. You may have a low grade bomb on your hands when it is charging, so treat it as if it is. It also may come back to life and be a good battery for years to come.
As a waterman on the east coast, I got to deal with this a lot. Just do be careful. If you want to go near it to see how it is doing, stop the charger and give it a minute. Then go near it. If you run a bare hand along the side and one cell is warmer than the others, that's "Game Over".
Good Luck
Matt