Compiz has a colour filter plugin. It allows you to transform any colour into another and it sounds like it might be perfect for highlighting colour blindness. What is instantly better than a browser plugin is that you can apply this to any window or even the entire screen.
You'll want to install
compizconfig-settings-manager before you do anything else. And one note before you enable it, you'll probably need to change the keys because they'll conflict with other plugins. The combination in the screenshot below worked for me.
If you can't find it, make sure
compiz-plugins-main is installed.
It seems like deuteranopia and protanopia are the filters you want. Just delete the ones you don't need and you'll be able to switch between the modes you want very easily. If you want to make any changes to the existing filters, look in