In general terminal servers won't allow you to do this. The problem being as far as I can see is mostly key mapping. Even if you can bring the machine down to OK> through your terminal, you then end up getting gibberish as you type.
But there are some pieces of hardware that do support it, or at least claim to. I have found that in some cases they fail to meet published specs. Unfortunately I can't remember the name of the one system that worked. I do remember that it was a pretty expensive PC based KVM system made by a British company.
But this is academic really as you already own the terminal server system. Unless your terminal server system supports this functionality you're out of luck. If it, does consult the manufacturers support to find out how (they all seem to be slightly different).
Sorry it couldn't be better news. Ian
"IF" is not a word it's a way of life