Febreeze also works well...
Bad idea. Febreeze doesn't have any anti-bacterial agents. It's essentially a perfume; and in many cases, the build-up from the liquid gives a good base for bacteria to grow. If it's pretty bad now, though, it'll take a lot to get it clean.+1
whatver u cant wash.. febreeze it!
Use a good but strong fabric soap and scrub the inside of the boot really hard. I would use a combination of lysol & baking soda afterwards for whatever smell is left.