Try this the oldest user guide i have is the xxiie and xxe

1-Do not lift the handset.

2-Depress the # [or rdl ] and * [or rep ] keys.

3-Press the line key you want change.

4-Dial the telephone # to be stored [16 digits max ]

5-Press the # [or rdl ] key to store.

6- Repeat the above for each line key

It may be necessary to insert a pause after trunk access code to allow for dt delay .If so ,press
the MW/FL or PAU key after trunk access code.