I wouldn't attempt it unless you have done it before or are very mechanical minded.
The rears are easy as sin. Two bolts to remove and drop the rear beam, pull out springs, slot in new ones, jack up the rear beam in line wit the bottom of the shock, screw in and away you go. 30-40mins will do the rear springs.
1 hour each or there abouts will do the fronts but its a bit more ticky.
I did a very quick write up the other day on how to do the fronts but its very basic. You have to remove the front calipers, disconnect the droplinks, remove the brake and hub from the drive shaft, undo the 3 bolts on the top mount under the scuttle panel and thats the whole front suspension of one side out.
Remove top mount from suspension, remove standard spring, insert uprated spring, reattach top mount and then reverse process the installation.