How do I split a manual transaction across mulitiple categories e.g. Salary, Dividends, Expenses (not using SmartPayments)

I've noticed that if you're explaining an existing uploaded transaction, you can enter an explanation for part of the transaction value and the rest of the transaction is still unexplained, to the tune of the remaining amount. This is good since it allows me to split a payment to myself amongst the categories; 'Salary', 'Expenses' and 'Dividend'. Is it possible to do the same for a manually inserted transaction? i.e. split it amongst multiple categories as is possible with the uploaded transactions? I cannot use SmartPayments for this since I am entering historical values and need to control exactly how much is allocated to each category.