I love Dwarf Fortress. DF is not /tg/ . Fuck the 'Commander Keen' rule. There is a thread for DF on /vg/, which is a VIDEO GAME BOARD. /tg/ is a TRADITIONAL GAME BOARD.
You are asking how to mod a video game on a board that is not a video game board. This post does not belong here.
To not be a jerk and to actually answer your misplaced question, it is entirely possible to mod DF to have a radically different setting. There is a bloody Pony version, some post apoc one with firearms. It would be super easy to throw a bunch of Greyhawk/Forgotten Realms/WFRP/Star Wars/Whatever Fantasy Setting into the DF data files. Worlds are randomly generated, so you could not easily re-create the precise geography or history of a pre-established setting.
Also, as >>62999265
points out, magic is not yet implemented in DF; any spell or magical effects are going to have to be cobbled together from the already existing effects (fire, webs, white fluid, dust from Great Beasts, et cetera).