I just finished mine, a 2 door, a couple of weeks ago. I did it with the window in, but it was a warm day and the window rubber was quite new and pliable. It was still a challenge to the fingertips though to get the rear wire under the hooks.
The risk of ripping the headlining whilst fitting it? - It is more likely to rip the old one, the new ones are a bit more flexible (being new).
Fitting the wires? - Not hard. I found the old wires could be de-kinked quite easily and threading them into the new lining was not too bad. Some plastic tape over the ends of the wire helped them not to snag.
Overall, it is not as bad as I thought it would be. It took an afternoon and a bit more of the next day. If you take your time, being prepared to walk away and have a coffee/tea sometimes, you will probably actually enjoy the job. One really good thing to look forward to, apart from the nice new car look and smell of your ceiling, is the satisfaction of having done the job.
One of the 2 clips you will need to deal to and the tool I used.
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The hoops and plywood front bit
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The end of the hoop, old lining
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Have fun.