A SOHO router won't be able to provide such feature. You could however use/create a software router.
Let's suppose, you want this on Windows... this is one:
http://virtualrouter.codeplex.com/[
^] is open souce. It has no time limit either, but as you have the source, you can add this feature.
But you could check a list like this:
http://alternativeto.net/software/virtual-access-point/[
^] (or seach for it on google).
This is an other approach, which is a little bit more compex, but much better:
http://www.chillispot.org/features.html[
^]