You can set up a position in the Analysis board and in the bottom right there is an icon of a robot. Then you can select a bot and continue the opening from the position you submitted.
Although I do have to say they're not the best bots I've played. The best training for me is an engine which I adjusted to think more aggressively. Fun games usually arise.
Is it possible to play against a computer that is set up to play a specific opening? For example, let's say I want to play the Queen's Gambit and I want the computer to play the Slav against me. Does something like this exist?