There's a project entry in garage, which is where the files should be. I haven't checked to see if they have been added for a while.

If you want to make the additions in a portable way you'll probably need support in Sword itself, which is in C++ IIRC. This is obviously the strength and weakness of using an external engine: you get free support for all engine features but adding new ones is probably hackish. The first step would be to approach the sword devs on the crosswire mailing list and ask what the current options are to support those features. If no good way is supported then perhaps they'll be willing to add one (finally), or at least describe how to go about it.

I wish i had more time for development as i already bit off more than i can chew for the moment and really would like to see katana become a killer reader...