To be able to edit framework (OAF) pages in R12 you need a few profile options set either at site but more realistically at user level. The following profiles should be set as follows for your user level values:
FND: Personalization Region Link Enabled
Personalize Self-Service Defn
Disable Self-Service Personal
After setting these above you'll need to log out completely and then re-enter the instance. In some instances I've seen that you need to bounce Apache or clean out cache from browser. So check those if you don't see the option immediately.