Have a generator with two 110 volt output's and would like to back feed a panel to the house that is already installed for this application. It has a 220 input to the house panel, can this be done .

Not safely, even if you have 240 volts between both hots, their is the possibility of one of the cords being unplugged making the Prongs LIVE and can shock or Kill.

I assume there is a transfer switch or some form of interlock.

You need to get a generator with the proper 120/240v output.

NOTHING is "220". It is either 120v. 240v. Or 120/240v.