Smarty

[smarty_user]

I've written a plugin to create a vertical menu, and in so doing, it populates an array called $smarty->PreloadImages with the names of the images to preload on the page. I've written another plugin to create the body onload call with the image preloading. To wit:

[boots]

This is never fun.

In your case, since you are populating an array, you have a way of knowing whether you need to insert code -- after the fact. You can exploit this knowledge via an output filter which, if it detects a populated array, would automatically find and rewrite the affected portion of the output. Not pretty, but it should work for you.