Same way you would tell human musicians what tempo you want: put a tempo marking in the score. You can do this by clicking the appropriate note of the score and pressing Alt+T or using the Tempo palette. See the Handbook under Tempo for more information.
You can temporarily override the playback tempo via the play panel (View|Play Panel or F11). Marc's suggestion is the way to enter a tempo that is saved with the score.
Comments
Same way you would tell human musicians what tempo you want: put a tempo marking in the score. You can do this by clicking the appropriate note of the score and pressing Alt+T or using the Tempo palette. See the Handbook under Tempo for more information.
You can temporarily override the playback tempo via the play panel (View|Play Panel or F11). Marc's suggestion is the way to enter a tempo that is saved with the score.