You'll have to explain better what it means to score pages. For example, score based on what? And where is the scoring supposed to be displayed?

Maybe like this. Though it doesn't matter where the scoring, it's better to have it on the page.

Creating a voting/rating mechanism in user scripts is extremely problematic, as the only place the script can store the voting information is on a page visible to everyone and editable by anyone.

I know dev:AjaxPoll.js can achieve this effect. Yet it seems unavailable in some wikis where discussion boards are not enabled. So I want to find a way to bypass the discussion boards.

Storing the information on a public page may not be matter. Because users can view the history and revoke the tampering.