Hi Adrian,
I downloaded it the other day and am tinkering around with it. When you say spec rcds and rcbos, do you mean provide your own specs or just change the device on that circuit?
If it's the later, it has a big list of predefined devices. Double click the circuit at the distribution board (the 1.L1 box say) and in the edit circuit page that pops up there is a tab for changing the protective devices. Click the 'Change' button under the device and you'll get a dialog allowing you to select from the list of available devices.
For speccing your own, not a clue, sorry.