Snippets and $selected$

In a snippet I am trying to create, I am wanting to show a dialog when the user starts the snippet and have the user specify some information in a dialog based off of the text that comes from the $selected$ replaced (ie. the text that was selected before the snippet was invoked).

Is there a way to do this (ie. get the text that was inserted for the $selected$ replacement?

Thanks,

Ashton