In Sage, we have always just set our credit cards up as a bank account. They then show as negative balance and when we pay the credit card we use bank transfer to take money out of main account and increase credit card account back to zero.

As we have more then one credit card, it was hard to track who paid what, so we ended up making a bank account for each company credit card.
This also has it's flaws however, for example we get a single statement and make a single payment (so we have to split this up manually when putting into Sage).

It would be easier if Sage adding better capibilitys for handling credit cards in Sage, and for example the ability to record a credit card name/user to the payment.