software to help paydown mortgage

I want to pay down my mortgage using a HELOC account.
I would send all Monthly income into the HELOC & use it as a checking account to pay my bills including my Mortgage.

Can anyone create a Software to prompt me when to make lump sum Payments to my Mortgage principle as it notices the HELOC balance owed is low or approaching zero?

In other words, I can?t deposit my income into the HELOC if there isn?t a balance owed on it?thus, I would need the Software to tell me to send a large payment to my mortgage principle to increase my balance owed on the HELOC so my Income can be deposited into the HELOC.
Thanks in Advance,
Bill