Andy_Langton - 8:40 pm on Apr 2, 2012 (gmt 0)
Google is going to revisit and re-evaluate those pages on its own schedule - primarily based on the links into the pages, and how important they are.
The "brute force" method is to request removal, but I wouldn't normally recommend it. Otherwise, you can submit a sitemap of the erroneous URLs which will speed things up somewhat.
When it comes down to it, though, if you struggle to get Google to revisit URLs, then they aren't very important in the general scheme of things!
Is there a particular problem with the URLs you're trying to remove?