Ok
First you need to find out if any memories have been allocated. Check commands 73 and 94. If there is no allocation then you have the arduous task of working out what memories are available. This isn't easy as they are spread across the two commands and can overlap, they can even be allocated to multiple stations. Once you have the next available blocks simply assign them using either cmd 73, cmd 94 or both. Cmd 94 allocates memories to the dedicated one touch keys. Cmd 73 allows you to add them to the programmable keys using a setting of F11XX where XX is the memory location. and if you want the DSS function you assign the memory in both.
See here for DSS programming....
http://www.tek-tips.com/faqs.cfm?fid=6338