Creating a collection file in simPE (for walls and floors)... How's it done?

[thasimniz]

Does anyone know? This is the best bit of info I've found over the last several days of looking:

http://simpeforum.ambertation.de/forum/viewpost/13008#13008

I'm hoping there's an easier way of doing this. Otherwise, just creating the file in-game would be faster. If anyone has a tutorial specifically for this, or any relevant info, I'd love to hear about it.

Thanks!