Buy a tube of exterior grade frame sealant and a mastic gun. Poke the application nozzle through the hole from the inside and squeeze out a fat blob of sealant. Pull the mastic gun back inside - hoping all the while that the blob forms a good seal.
Take a long bamboo garden pole and press down on the blob from above in an attempt to make a good seal.
I have no idea if this will work but it sounds like fun to me.
Alternatively pay someone to replace the damaged panel.
Good luck...
Peccavi
March 2011