Using pagination library with custom routes

[eluser]digity[/eluser]
I'm trying to figure out how to I use the built-in pagination library with my custom routes. For example, $route['topic/(:num)'] = "topic/view/$1"; makes it so I can have the topic_id follow the controller segment of the URI for a cleaner URI (i.e., www.domain.com/topic/4387). Given my route configuration, what's the best way to set up pagination for a landing page (www.domain.com/topic) AND a single item page (www.domain.com/topic/4387)?

Thanks in advance