What I like to do in situations like this is boot without startup-sequence, set echo on, as Thomas described, then execute s:startup-sequence. If you append >dh0:logfile it will save the buffer to disk.
Hmm, are you sure? I was under the impression that each command handles redirection by their own.
There's also an interactive mode - set interactive on, maybe? It'll ask you to confirm executing each line of the script.
I'm fairly sure that there's no such thing.
