The only way I know is you remove all the flesh you can manually, and the you put it into a terrarium full of beetles. The length of time depends on the size, but a grizzly skull takes 5 days. I'm not sure about mounting though, you should call a taxidermist. I'm in Calgary, if you, are look up Bruin Taxidermy.

On another note what types of skull do you have? I am Desperately searching for a Wolf or some Wolf skulls.
if so are you willing to sell them?
E-mail me at babeboy10@hotmail.com