They should behave exactly the same as Minecraft command blocks, with the following exceptions:
To add a command block, you have to type "cmd()" in the developer console (Ctrl + Shift + D).
The commands have to be in haxe or xml.
There is a remove button and a direction button.
Some errors aren't caught. Syntax errors are caught, but errors such as an item not being in the game will not be. Due to this, a command block with the "conditional" option might run even if the command block behind it was unsuccessful at running its code.
Commands with errors (which can be caught) will be highlighted in red.
The following commands will also be added (mainly for developers, variables with question marks are optional):
"give(id, ?count)" will give the player an item with the id "id" for "count" times.
"call(id, ?count)" will spawn an object with the id "id" for "count" times at the exact coordinates of the player.
"tDum(?element, ?isSpirit, ?defense)" will spawn a test dummy with the element "element" and defense "defense", and will be a spirit if "isSpirit" is true.
"killTDum()" will kill all test dummies in the area.