The answer to this kind of depends on where the money went (that's a loaded question to ask!):
If the money went into an account that is set up in Farm Works (such as a checking account) or went to purchase an asset that will be shown on your books then I would tend to want to set it up as a real loan (just like any other loan). You could put it into a separate category of farmily living, however the family living account will get closed into your equity account at the end of the year, and if there is still a balance owed, it will get closed out.
If the proceeds of the loan were used personally and won't be shown on your books you could go into Payments & Purchases, and go into Family Living and use a category that shows what the loan was used for (such as "Car Purchase" or "Vacation" or whatever) and enter the amount as a positive number. You could then go back to Family Living and set up a category for the loan (maybe call it "Personal Loan") and enter the amount as a negative. The only drawback to this will be if the loan carries over into the next year (as I stated above).