If you'd like to trick your MicroStation (V8 - sorry, Dub!) into accepting AutoCAD commands, there's a variable called MS_DWG_COMMANDPREFIX that sets a user-defined character (ours is \) to precede AutoCAD commands in the key-in window.
For example, in our case, the keyin \line would invoke the line command, \copy the copy command, etc. BTW, the key-in window is found under the utilities drop-down.
I hope this helps somebody out there - I could have DEFINITELY used this a few months ago!
PS...enter your desired character between quotes i.e. "\"