Time compression is a special one, there is no game command for that. However, it can be set via script. I suggest you wait for the next version of this mod, which implements that. It takes a little bit too much time to explain how it is done, but you will see later (and can change it to your liking). The speed/depth/rudder/course changes which take a spoken number are done in a similar way btw. Be advised, I will change the grammar definitions still, to support extra languages etc. so keep track of your own changes because you will have to redo them later...
[edit]The speech engine is set up so that it automatically reloads changes to both XML-files, so you can have the game running (or the test app), while editting the files and immediately test the new commands.
(in the odd case, it may CTD the game though, in case of file locks but this is rare)