You could purchase some items on your Slate card that are easily converted to cash, then take the cash to pay down on the card you were looking to transfer a balance from. I've been doing this with a Citi card I have that has 0% purchase/balance transfer APR for 18 months, but there is a 3% balance transfer fee.

If you need ideas of items that could be easily converted to cash, check out the Manufactured Spending forum. If you go the Vanilla Reload route you could effectively transfer as much as you need for slightly less than a 1% cost.