Park the deck on a pair of kitchen chairs to provide the purchase for driving skewers into the outriggers, taking care to snip them to a suitable length prior.
(There's no need to throw away the off-cuts as they can be used farther along.)
If an off-cut is reluctant to be driven into the foam, often it will if you try the other end as there's no telling what goes on in the mind of a kebab-skewer.
