A new command has been added "Creativextra" (or shorter: cextra). This opens a window with some extra items, simply click them to add them to your inventory.

Current items in menu:
Forever burning furnace
Cocoa bean block
Farmland
Redstone torch off

If there's any other blocks you want to see in this menu, just post here.
Be aware that some blocks won't work well (for example the redstone ore on block), because as soon as they are interacted with they will revert back to their normal behavior (which with redstone ore happens when walked on/right clicked).
This also happens with blocks like the redstone torch off, however the redstone torch at least can't be changed by players not on the worldguard.