I did something similar a while back when I made my RANDOM SELECT category.
I made all of those "randomselects" to "-" and put the only "randomselect" in the RANDOM SELECT category (put two of em). then I went into my system.def and made it so the cursor won't wrap. because it won't wrap, and because it won't highlight empty boxes, the SECRET category is unselectable unless you highlight RANDOM, move right one, then down one.
you'll also notice that thanks to this method, the SELECT, although being a seperate category, cannot be highlighted.
there are still some errors with this due to character placement, but once I have all my stuff added, I'm going to only put secret characters on lines that aren't being used by other categories, to ensure you can't get into the SECRET category from another category by accident. (for example, highlighting blodia in the MECHA category and pressing down will put you there right now.)
here's my select.def so you can see what I mean:
http://www.tehinter.net/uploads/catselect.txt