Thats actually not to far off from what I seen online somewhere ( can't locate it now) but the person used a sight glass vertically on top of their conical with a butterfly valve and a cap on top of the sight glass with a gas in port. Load the hops, add the gas in plate, pressurize and open the valve. Presto!! hops go into the fermenter without o2. I can def find a 4" sight glass but can't seem to find the gas plate.
I made my own "gas plate". I ordered a female Tri-clover to female NPT fitting from Brewer's Hardware and a and a male NPT ball lock keg plug from Foxx. I have also made one with a brass nipple that has NPT male on one side and a flare fitting thread on the other that I got at Lowes. It isn't exactly a perfect thread match for the keg plug, but it worked. Obviously, the Foxx keg plug is better.