Flash Catalyst doesn't currently expose the functionality to do this, but you can enable the back/forward browser button if you take your project over to Flash Builder. I think this is a feature that would be useful to add to Flash Catalyst in the future.
Flex has a concept called "deep linking" that makes the html wrapper and hosted swf file communicate to enable the back/foward button
Select Project > Properties.
Select the Flex Compiler option.
Select the "Enable integration with browser navigation" option.
More details are here: