Dear Sam,
because LayTheme is written as a single Javascript-Application some things are not possible.
For example use extra post types, or include some jQuery scripts.
Also it is not recommended to modify the theme files, because the changes will get overwritten with the next update.
It's all a compromise. If you want to use those features, I recommend to have a look at LayGridder.
Hope I could make things clear :-)
Best!
Marius