If you have access to the local machine (which it sounds like you do), there are various programs to *share* the shell. However, this, in the instances that I have used it, require it to be end user initiated. If this is what you are looking for, then kibitz is the program you will want to look at. Screen also contains this functionality.
The other thing you could do is just restrict the user to only 1 shell, and tail -f the history file, if you want to see a running history of commands issued. This is useless though for seeing anything that is not a command.