Hi,There are lots of options to do this.
Building your own redirect within the site is the best way to do this. The best option is to build a redirect file in c#/vb and search using RegEx for the old URLs and redirect to the new URLs. http://forums.asp.net/t/1844542.aspx Old post but sill a useful resource.
Or you could add all the old URLs one by one and redirect to the new URLs if you want to avoid Reg Ex's.
You could also try using the WebConfig if the above doesn't work.
<httpredirect enabled="true" exactdestination="true" httpresponsestatus="Permanent"><add wildcard="OLD URL HERE" destination="NEW URL HERE"></add></httpredirect>