I used the supplied gaskets when I did mine, and here about 3 years later I have no leaks... but it was only a daily driver for a year after I did it.
What I would do is like said before:
Remove plug wires and spark plugs and keep them organized so they go back in the same place (THIS IS A GOOD TIME TO REPLACE THE PLUGS)
***When removing header bolts, BE CAREFUL! If you break these off, it will cost you dearly! NO IMPACT TOOLS!!!!***
remove the two end bolts and thread them back in a thread or two, enough to hold the header without breaking a thread.
then remove the rest of the bolts (I usually keep them organized so they go back in the same spot, but Im alittle OCD, This is not actually necessary)
you should be able to pry the header back enough to slide the gasket out and slide the new one in. this sounds simple, but this IS a 5.0 explorer...lol
The gaskets will likely be stuck to one side or the other, and getting them out without taking the header out can be a pain.
Personally, I would remove them altogether and prep the mating surfaces with a angle sander and cusion pads, because buildup of carbon and remnants of the old gasket will mess up your seal with the new gaskets...
but you said you want it simple, so there it is. if youre careful and get the gasket placed correctly and TORQUE THE BOLTS IN SEQUENCE!!!!!
remember the bolts have a torque spec, I believe Bob Pasquale included this int he instructions with the header.... I dont have mine handy but Ill try to find it.
EDIT: The stock manifold was 30 Ft-Lb..and I believe it was the same or similar. if you use the thread locker supplied or get some blue locktite (high heat stuff) you shouldnt have any backout issues, but dont over torque them...
If you over torque the bolts or torque them out of sequence the flange can warp, and no matter what gasket or header you have, it is very likely that it will leak.
if you need pics and such of mine, heres my thread on this:
*Mutineer's Torque Monster Install*
let us know how it goes and if there are any issues...
DRF