On the HS748 we can use it at any speed, but it is better to use the rudder above about 80kts.
The HS has no link between the rudder pedals and nosewheel, so at any speed where the rudder is ineffective, you must use the tiller. I would use the the tiller at high speed mainly in a strong crosswind, where the rudder quickly becomes useless. Sometimes on take off you need the tiller to keep straight almost until rotation. As a matter of interest, the ailerons into wind makes the steering a little easier on.
I don't think there is any compensation on the steerage angles for different speeds. Maybe on some of the advanced aircraft?