Usage:
/INPUT text
Enters text into the input buffer as if it had been typed at the keyboard, without deleting the current contents of the input buffer.
/Input is perhaps most useful in combination with /bind, to create short key sequences that expand to longer text. For example, if you have this binding:
/bind ^[oj = /input OliverJones
and then type "page ^[oj = snausages!" at the keyboard, it will appear in the input window as "page OliverJones = snausages!".