The remote control only have two buttons, on and off. These "actions" is the only one the receiver understands. So these are the only ones TellStick can send.
To dim the receiver with the remote control you press the on-button twice, the receiver goes into dim-mode and starts dimming up and down. To stop the dim-cycle you just press the on-button again. You have to do the same thing with the TellStick. Press on twice to start the dimming and press on again when the receiver is in the right state.
Since the receiver doesn't understand any other signals this is the best we can do. The selflearning swithes on the other hand also understands "real" dimming commands. With those it is possible to send a "75% command" to the receiver.
The problem is the receiver, not TellStick.