At the vast majority of special pages (for instance, Search), links that help user to choose how many results per page should be shown (i'm talking about "20 | 50 | 100 | 250 | 500" block), have .mw-numlink class. That helps to customize them a lot. Unfortunetaly, there is no such classes at Special:Whatlinkshere. And it seems to be the only special page without this class. I temporarily fixed my userscripts by using $("#mw-content-text > a:contains(500)"); selector, but I'm not sure if thats' a good solution.

There's also no human-readable tooltips at some special pages: all tooltips at Whatlinkshere look like "Special:WhatLinksHere/Main Page", while at search page they look like "Show 50 results per page".