Jonathan - are you saying you have a conference that will *last* 5 days or that is coming *up* 5 (or 4) days from now? To do Open Space there is a bit of pre-work (design, logistics, prep for documentation, selection of certain types of rooms over others, seeing if the time available can support OS or is too short for OS' - so if you need to check in to talk about this feel free to email me directly at lisaheft[at]openingspace.net.
Also, as you are new to OS - some places to learn more:
Harrison Owen (the method's originator)'s book "Open Space Technology: A User's Guide"
Workshops (I give them and can refer you to other colleagues who give them in different regions of the world)
Welcome to the Open Space world community space, Jonathan!
Just a note - from your discussion it seems as if you are new to Open Space ? As you mention things about design and such that are not how OST would exactly work. If I am assuming incorrectly thank you for correcting me - and if indeed you are new to Open Space, let us know and we can share with you some resources for learning how the process works...so you'll know more about how it might fit - if you want to use OST - for the conference you are inspired to host...