I did this to my MSD 8mm wires about 6 months back and used a combination of straight and 90 degree elbow boots depending on header clearance.
You can get the boots and terminals from summit.
http://www.summitracing.com/search/part-type/spark-plug-wire-components?keyword=spark%20plug%20wire%20boots For the crimping tool that depends on the type of terminal. The MSD spark plug terminals where more than my crimp could handle so I used pliers to get the terminal ends into position and then put a nail punch in my vice with the terminal on the end and slowly wound it in for a tight fitting head.
This how I went about changing the plug ends:
If all of your wires are quite a bit too long the job is quite easy, simply cut of the old boots, take the insulator back a bit and crimp on the new terminals.
If however not all your wires have spare length and the boot needs to changed, don't try just pull the boot off. On my MSD wires even after heating the boot it was too stiff and I ended up snapping the wire inside the insulation. I had to order some more wires. 2nd time around I put the plug in my vice and cut the head off with a dremel, much neater.
Getting straight boots on is simple, just push them on. 90 degree elbow boots are a bit harder because you have to line up the boot end and the terminal head. I found the terminal tended to rotate slightly while going in. Greasing the wire before you put the boots on is much easier, you can rotate and adjust the position of the terminal with ease.
Hope this helps