As far as I know, there is no shortcut to do what you say.
You can rapidly add an action by hitting <CRTL><SHFT>K, but the project field and action field are blank.
As a workaround, you could add several actions this way and save them without project assignments. Then, in a view grouped by project, you could drag and drop them en masse from the project = none group to the correct project. This will change them all to the new project at once.
Bill Kratz wrote a macro called GTD Police that will detect when a task is marked complete and automatically prompt for the next action. Maybe this code (available at the netcentrics site) could be adapted to do what you want.
Another workaround, once ou have the first tasks created, you can use copy-past to make another copy complete with project assignment. Then, just edit the subject line of the copy.