Ian -- I have the solution for you. But first...
[rant]
Good grief! I wish you telnazis would go away. If the someone wants/needs to run telnet, that is their business, not yours. If you don't want to use it, don't. Be happy in the knowledge that YOU have seen the light. But don't try to force your bigotry on everyone else. I've had sysadmins tell me that they'll not permit ssh access because ssh is insecure -- "You know, OpenSSH has been exploited, so we don't allow it here..." -- so we are forced to use telnet and ftp!!! Stupid, yes, but there is a thing out there called "The Real World" and it is filled with all kinds of less than ideal scenarios. What we need is flexibility, not technorighteousness.
Anyway, I'm sure most of you telnazis still operate those evil fossil fuel powered vehicles, so just how sincere is your zealotry to not use out of date technology?

[/rant]
Ian, telnet support is still there. You just can't ENABLE it from the web manager. If you DO enable it, the web manager will then tell you it is enabled, in pretty red text, and nag you to turn it off. Ignore that ;~)
To turn on telnet, you'll need the command prompt:
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/sbin/e-smith/db configuration setprop telnet status enabled PermitRootLogin yes access private
/sbin/e-smith/signal-event remoteaccess-update
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BTW, telnet was broken in 6.0 prior to 6.0b3.