Create: Start>Programs>Cadence>Release mm.nn>PCB Editor Utilities>Pad Designer, set the drill, if required and Layer details, single layer mode for SM pads.
Modify existing: in PCB Editor, load BRD, Tools>Padstack>Modify Design Padstack, Options tab, pick the padstack from the list, or select the padstack in the design, Instance (this one only) Definition (all like this), Edit Pad Designer starts, change parameters, File>Update to Design to set teh new parameters, right-click>Done to confirm.
Reference, algrolibdev.pdf in the doc\algrolibdev directory of the dictionary.
I am pretty sure that the Mitzner book omits the use of the Options tab, worth pinning this tab out!