There's freaking old (first weeks of my gm times, iirc) ~logautosave command which does familiar thing - once used, it appends any incoming text to autosave.log until you close the client. I've never made it official command, due to some (dirty) tricks which kicks in before text is displayed in client and fact that i never saw it as thing which is actually needed for regular players; it wasn't worked on since written and left in "it's fine as it is" stage. It may also cause slowdowns in maps where lot of text is floating around. And oh, command was never used by someone else than me, one or two gms (but i doubt even in that) and few people who found it (hi jan0s1k!) when scripts was sent to client in text form. That also means that you should expect unexpected results due to lack of proper feedback ;p