Depending on what exactly you want to do with the highlighting, it can be as easy as using $replace.
In an on text event, halt the normal text and echo out an updated version that include $replace($1-,pball,pball) -- Needs the control code there... I can't do control codes from work. And if you want it to highlight when you type as well, you can do the same with an on input event.
Now, you can improve that by adding dialogs that let you set up highlighting without having to manually edit the script each time. You could also take and make it less likely to highlight incorrectly by having it check the tokens (words) and make sure that it matches the entire word (not counting punctuation).
For example: Hello, pball.
But not: Let's play opball.
Doing that just requires looping through the words and checking for a match while ignoring punctuation.
However you do it, that's really not too much work. Setting up a dialog to handle it so you don't have to manually edit the script anytime you want to add more highlights would be the most work... the rest would go pretty quickly. You might even add in traytip popups for highlighted text if you wanted to.
If you've already started trying to make it work, you might want to post what you've got and explain what isn't working right and someone can help you fix it. Easier than asking someone here to write the whole thing from scratch.
