All you need to do is start up the creation kit(I assume you know how) and go into the spells catagory.

From there find the slow time shout (enter 'time' in the search box) duplicate it, then edit it.
Choose whatever name you like for the ID I usually put Myspell so I can find it easier, then name the spell, After that, change the shout to a spell in the drop down menu, and for casting put eitherhand, then edit the spell itself and in the magnitude field put 100.00 and set the duration to 16 seconds (haven't made it last longer because game might crash) save, put it in a tome and put that in your world.

From there find the spell (wherever you put it) and play.

Hope this helps.