Power scrolls can't be "made", but the scroll binders can, through a complicated practice.
The Binders were introduced just a couple months ago. They allow a person to combine a number of lower-power Powerscrolls, all of the same level and skill, to make the next higher scroll level. So, for example, you can combine a bunch of 115 magery scrolls to make a 120 magery scroll.
More information on these can probably be found on the Spellcaster forum in the profession section of Stratics, as that is the board for discussing inscription.