I have did several and turned out great.
you can order , whats called liquid ear liner from any taxiderist supply catalog on the net.
I take this and formaldihyde and mix 50 - 50 . cut around the base of each horn , take a hypo and start at the tips,(do not split), inject the mixture into each horn,go to each tip and do this and you will see the blood start to run out at the base.move down each horn from the tip a couple inches,then down another inch or two till you reach the bottom.do this until all you see coming out is the clear liquid.
set aside to dry(inside so nothing can get at it).after a mo. or two they will be OK.

I have several at home that are 10 12 years old and look great.