Silver Surfer is pretty much on the money with the front bumper.
With the SS grill you will need, I have seen them on EBay selling for the same price as what you can buy them from Holden for, (Funny that) so grab a new one, just as easy.
There are two or three Ph head screws in each fornt wheel arch. Take them right out.
(easy to do with the front of the car on the jack and the front wheels off or just use a stubby screwdriver to get in there or even turn the wheels so there out of the way.
Next remove the screws at the front of the bonnet holding the top of the grill on.
Then the Exec grill is either clipped to the bumper or screwed on either way remove it.
I think under or around the number plate area are some scrivits remove those little buggers as well and try not to stuff them as you can use them again and there bloody expensive new.
Once all that is done go to the left hand wheel arch and place you left hand around the end of the bumper towards the top and the right hand gently against the bumper to give it support.
Now pull the bumper with your left hand and there are a series of lge white clips across the top, they should all pop off and the right hand like I said is just supporting this move.
Do the other side and the bumper should just fall off.
Then repeat in reverse to fit the SS bumper but the grill goes on slighty differently, no biggy tho.
The side skirts, now let me think.
Two or three Ph head screws at the end of each skirt in the wheel arches, take them all out.
Open the doors and remove the lge rubber seal and under that you will see oh say 10 or so scrivits (bloody things)
Gentley remove all of them apart from the two end ones as I left them till last then popped them off last.
The skirt should pretty much fall off if I remember correctly.....
Oh and with the skirt there is a end cap as you will see, it goes on last, I'm pretty sure.
It was a while since I did mine.
If I have missed any thing out then please feel free to add it in.
In the pics I have added it should go from this to that....
Windsurfing.....