Japanese and Dutch Reverse Auctions

Hi,

I've been using reverse english auctions on Ariba having previously used Agentrics, but wanted to look at the possibility of using dutch or japanese auctions as an alternative.

Does ariba have the functionality to set them up in the same way as one would for a reverse english auction?

My colleagues think they are possible but they have to be set up as a custom auction, if this is a case could someone talk me through this?

any help would be very welcome.

Ed