I have done it before, and it was easy… relatively speaking. Its the hanging of the door after that gets a bit awkward…
On the other hand I have never tried to replace the flywire in the door with “PetProof” wire. Dear heavens, its a nightmare. I took the door down and had the old wire out and cleaned the door in prep for the new stuff, and then found that my usual method (screwdriver and brute force) was simply not going to work this time.
Off to Bunnings for the spline roller… but which one, double ended or single, with a sharpish bit at the end (god knows what thats for… poking I suppose)… decided on the double ended, with a convex + concave roller. Home again and into it before the storm comes. Ha. Its now 45 minutes later, I have got skinned knuckles and am covered in bandaids to avoid further bleeding and I am still only halfway done.
PetProof flywire is really heavy duty and it does NOT like being put in ordinary doors. I don’t know if there’s any other kind than ordinary doors, but I shan’t be bothering with this stuff again. If Thomas William destroys it, then it can stay destroyed. Over it. But I should go finish up.
 Some time later: I had to call a friend to come and help. It was hilarious, we are both decrepit and our knees are in bad shape, never mind our other joints, but between the pair of us, stumbling and fumbling, the door is complete and back in place. However, again, I say… no more petproof flywire. Ever. End of.