Help with placeholders

I have been playing around with the placeholders plugin, the one that inserts [[ Date ]] in yellow. I'd like for the placeholders to be treated as non-editable blocks. The plugin already selects the whole placeholder when I click on it, which is great. However, I also would like,

* Select a placeholder when I move the cursor somewhere within that placeholder.
* When the cursor is directly to the right of a placeholder, typing any text should be part of that placeholder.

I suspect these are fairly easy if you know what you're doning. Since I'm new to FCK I don't know what I am doing, so I'm asking .
Paul