Write a blog post to PlanetKDE making people aware of the cross-desktop room program (highlight a few talks) and ask them to sign up to help at the KDE booth on the wiki. Post the text here before publishing it on PlanetKDE.

https://fosdem.org/2013/schedule/track/cross_desktop/

http://community.kde.org/Promo/Events/FOSDEM/2013

http://dot.kde.org/2012/11/16/fosdem13-excellent-opportunity-kde