@Jay P.
Your debt service coverage ratio actually does not improve. DSCR is a measure of the property's ability to cover its debt service payments.
NOI/Payment, not (NOI+(Other non-related income))/Payment.
There are only 2 ways to improve DSCR:
1) Increase the numerator (NOI) either by increasing income (of the property specifically) or by decreasing expenses (tax abatement, lower insurance premium, restructuring leases to put more expenses on tenants, etc). Even lowering your vacancy rate will not likely accomplish this because NOI, for the purposes of DSCR analysis anyway, will likely use an automatic value for vacancy rate.
2) Decrease the denominator (debt service) by getting a lower interest rate, extending the amortization term, etc.
It's important to remember that a lender will not want to rely on your desire to inject other funds into the property in order to keep it afloat, regardless of how much money you make, unless you sweeten the deal somehow (maybe a collateral position in another property like a second lien on your primary res or something). If you are willing to do that, you will want to look for a local portfolio lender to structure that sort of cross-collateralization; a conventional lender won't do it.
If this is a purchase, the bigger question is, why do you want to own a property that doesn't cash flow? If the DSCR doesn't work, then either the price is too high, or you're trying to leverage too much of the value (which the lender won't allow anyway).
If this is a refi and you're trying to access equity for other purposes (like more investments), be careful, you're heading down a slippery slope.
Hope this makes sense,
Troy