I was in a class years ago where a Fel-Pro rep stated that there was no need to use sealer in addition to gaskets. The gasket was there to do the sealing.
With that being said, i will use various chemicals depending on situation. On something like your side cover, do, of course, make sure the mating surfaces are as close to flat as possible. If it wer mine I would then likely use Permatex Super 300 to glue the gasket to the cover, and make sure the block side is dry and clean.
I use this same method on the valve covers on my BB race car and have to change the gaskets every couple of years, but I pull them probably 10-20 times a year for inspection and adjustment.
Devin
