Working in conjunction with Lasher, the head coder from Aardwolf, we have put together some telnet protocols for exchanging "out of band" data between client and server.
The general idea is to allow the exchange of information between client and server at time when entering simple MUD commands may not be effective - for example during character creation, or when AFK, or at a pager prompt.
This uses SendPkt for MUSHclient to send protocols to the server, and the new ability for MUSHclient to react to IAC SB 102 ... IAC SE messages from the server.
A lengthier description is available at the Aardwolf blog:
Using telnet negotiation to control MUD / Client Interaction.