"Well, you sit on the seat, and scoot the dalek along the floor with your feet. There's a crossbar you can hold onto with one hand to give you better control. With your other hand you operate the sink plunger, with your third hand you move the gunstick, and with your fourth hand you move the eyestalk and operate the lights while remembering your lines so you can synch with dalek dialogue coming in over the speakers."
I fully recommend spending some time as a dalek operator as it will furnish you with the extra manual skills and dexterity you will need before attempting such things as nappy changes and baby baths.