Valve Stem Seals!!!!!!!!!!

I think it is possible but I am not sure if it's any easier. By the time you get the cams out you could have the heads off and not have to work standing on your head.

It's possible. You need to fill the cylinder your working on with compresses air and a specialized valve spring compressor for that application. Just curious. how come you need valve seals?

Getting white smoke from your exhaust on start-up?

Usually, speaking from my experience, white smoke means that there is coolant entering the combustion chambers. If you had issues with valve stem seals leaking the smoke would be a blue color from oil burning. My uncle had a 99 Camry with the same 3.0L eng as your Avalon and his was smoking on start up, but he had blue smoke. It was oil being burned, in his case he had sludge issues which clogged up the heads and forced oil past the valve seals into the combustion chambers.