Running with no pressure in the accumulators won't damage anything, but it's not safe; the accumulators effectively act as a battery for hydraulic pressure. In the event that you lose the drive belt, or the pump fails, you'll find that you suddenly have _very_ heavy steering and no brakes, other than the hand brake.
If you don't have the equipment yourself, any hydraulics shop should be able to charge them up for you for a moderate fee.
Cheers,
Terry