Since Tiger or Jaguar I am using a more or less dedicated "swap volume". In Leopard and Snow Leopard it's possible to record in /System/Library/LaunchDaemons/com.apple.dynamic_pager that swap volume:
defaults read /System/Library/LaunchDaemons/com.apple.dynamic_pager
EnableTransactions = 1;
HopefullyExitsLast = 1;
Label = "com.apple.dynamic_pager";
OnDemand = 0;
ProgramArguments = (
"/bin/wait4path /Volumes/virtu/ && /sbin/dynamic_pager -F /Volumes/virtu/.vm/swapfile"
AppleJack, since version 1.4.x, I think, never checked that file to determine the location of the swap files. Could AppleJack be improved to read that file?