You might want to wade through the RFCs that have interesting titles, though you'll have to apply some judgement here ... (e.g. TELNET RANDOMLY-LOSE Option TELNET SUBLIMINAL-MESSAGE Option)
I scanned through some of these looking for what I think you might want - the ability to tell clients "send me whatever you've got in your input buffer if more than X time has elapsed since last character entry". None of the RFCs seemed to mention such a thing.
But I might be confused as your two paragraphs above seem to contradict each other? You find character mode 'inconvenient' but are looking for a way to "instruct telnet clients to change their settings?"
Another bit of code that might be instructive is Net::Telnet which demonstrates handling Telnet option negotiation.
In reply to Re: Telnet Modes
by shenme
in thread Telnet Modes
by narse
For:
Use:
& & < < > > [ [ ] ]