Post the transaction to pay the interest as you normally would process a payment to that credit card. Except, when you go to the multiple distribution screen, 1. add an account for a "credit card short term payable" (you can add this liability account to the chart of accounts as you post the multiple distribution) and deposit the total principal amount that you are NOT going to pay with this payment.
2. Then enter the interest account and charge the interest amount you are paying,
3. and finally enter the various expense accounts that you are NOT paying and make sure the total charges of those equals the total of the "new" credit card payable account.
4. Click on "balance net" at bottom of your multiple distribution screen, and your total check amount should only be for the interest payment you are making.
5. Make sure that your short term payable account was set up correctly by verifying the liability position on your Balance Sheet.