You NEED worldedit, it searches for schematics in .../plugins/Worldedit/schematics or sth like that.
The command that the commandblocks use is:
/schempaste <schematic> <x> <y> <z> [world] [-a] [-e] [-b]
For example, to paste arena1.schem at coordinates 100 64 200 in the world named world:
schempaste arena1 100 64 200 world
