by frag.machine » Mon Aug 23, 2010 8:39 pm
The client would need to store the last N updates (where N = number of frames sent in the last 3 seconds or so) and replay it in slow motion.
Something that may be easier to do is to move the dead player camera to focus on the killer, pretty much like in TF2 when you get dominated by someone. But even that need some engine support.
I know FrikaC made a cgi-bin version of the quakec interpreter once and wrote part of his website in QuakeC 
(LordHavoc)