[GNC] Multi-currency split

[Fred Tydeman]

My home currency is USD
I have an expense account for groc. in USD
I have a cash account for XCD
I have a liability credit card account in USD
I buy some groc. in Antigua
I pay with 18.30 XCD (local currency)
and 90.02 XCD via credit card that shows as USD 33.49

I could record this as two transactions:
  USD 33.49 -> 90.02 XCD;  credit card to cash
  108.32 XCD -> ??? USD; cash to groc expense
How would I record this as one transaction with splits?
And, in which account should I do this?