[Bordeaux-threads-devel] Is there a multi-implementation way to get a timeout on condition-notify?

On lispworks (6) there's condition-notify-with-timeout. On SBCL - not sure - there's a with-timeout that can make a form throw; but a little birdie told me that it's not supported on all platforms. Any good ideas? I've toyed with ideas for emulating it; but they tend to fall down under scrutiny.