Changing plug wires

Is is hard to change the wires on a 4l 2001 Explorer? I haven't changes wires since I was a kid & they look a little different & I don't want to
damage them. Had the dealership install the plugs because they said they were really hard to get at. These were the plugs that were to be good for 100,000 kms. I was told that if you leave them in that they will seize up & then you may have to take the heads off to get them out. I argued & told them that that was Ford's problem but I was told where to go. Strange how my wires were found to be defective. I guess one has fallen out of the harness. I told them that again that was Ford's shoddy workmanship & that told me it is my problem.
That is why I want to install the wires myself. I don't feel like paying anymore thatn I have to.
Any info appreciated. Thanks,\ John

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