Customizing Opening and Endgame Training Databases For the ChessBase Interface?

I have Rybka 3 with the ChessBase interface (Fritz11 generation), but its main use for my has been analyzing games.  I haven’t used the training features much, and I do most of my work in ChessBase itself with the Rybka 3 engine running.  However, while digging through the help files I realized that the databases the Openings Trainer and Endgame Trainer use are customizable.

That means, for example, that if I cleaned up my personal openings book in ChessBase I should be able to play against my own repertoire.  Or, I can take the endgames from a book such as 100 Endgames You Must Know and play the positions against the computer (something I’ve done in the past, but manually, endgame by endgame). 

I’m considering playing around with this feature and sharing my results.  If any of my readers have tried this, share your experiences.