I have the 9630 BB tour and this is my 2nd BB. I have not figured out how to seperate my SMS and MMS till now. I am sure it is possible but this is what I did to make it work.
Download and install CrunchSMS
Then go to Options->Security->Firewall and set to block SMS
By doing this your SMS will come through CrunchSMS and your MMS will go to your default SMS/MMS folder
Yea I figured, that's why i posted this as a way for people that want to. my native sms/mms only has mms now and crunchSMS is handeling my sms, so it's working great.