Formatting in index

I would like to add some routine names that are marked up with  
"function" tags to my index. It is not a problem to get them to show  
up in the index, but is there a way I can get them to appear in the  
index with the same formatting that they would appear with in the main  
text? (I'm using FOP, is this a FOP issue or a DocBook issue?)

-Mike