I think you are misunderstanding.  I am entering a deposit prior to receiving the transaction from the bank, so there is no issue with matching the bank deposit. 

Since we don't currently have any un-deposited payments outstanding I can't show you an exact screen shot.

Regardless of that fact, under no circumstance will QBO allow me to enter a negative in the Amount column.  It simply displays the "This Value is out of range" message.

I've seen the article you refer to. The instructions simply don't work. That is the crux of the issue.