Hi Peter,
Manual JEV in this case indicates the bank charges which is already posted you need to select this GL account in line 1 of manual journal entry voucher and in the line 2 you need to again select the same account but this time you can add the cost center to it for the same amount.
So by the end of the posting this GL account will have balance and also assigned to a cost center to it.
Thanks
Lokesh Sharma