Unfortunately it helps to work for a company that does some sort of utility work where by you will get the mountain experience. If they do fire contracts like the company i work for then you will probably get trained up for fire/bucket work.
Keep an eye out on the job websites because some of those companies are looking for the basic requirements like aircraft type and time and will train you up especially if they need pilots.
Some companies will do siesmic work which is a very good way of getting longline trained and experience.
The fire specific will be on the job training as you never know what you will be asked to do or where you are going to fly.
The requirement/courses you have to do as Gordy pointed out have to be done and if you are in the SW the Grand Canyon Sign Off as well.
The checkride is pretty straight forward for VR but it all depends what aircraft you are flying (some easier to do this out of than others).
Good luck with your quest. Hopefully when you get to fight fires you will get a better season than we have had the last 2 years.
Fly safe.