Scheduled Transaction Druid - Add Principle

[M Prindle]

Hi everyone,

I just finished refinancing my mortgage so I used the loan druid to 
create the scheduled transactions for the new loan.  The loan payments 
match my documents, but I would like to make an additional payment to 
the principal.  How would I modify the scheduled entry to add in the 
transaction?  The entry appears to be the loan formula so I'm not 
entirely sure what needs to be changed.

Side question, how does the close books work?  I selected it, but the 
only thing it will let me select are Equity accounts.  I looked at the 
docs, but didn't find a clear explanation of the feature.

Thanks,

Mike