Ok so I did mine this weekend after fretting over it for six years. When I bought the car it had inserts on the rear and has always had more vibration than I liked, but as I got it older it bothered me more and more.
Since I was going through the trouble, I bought a new mount, but turns out the original is in mint condition because the inserts doubled as motor mount protection.
Here are my tips.
First of all, the top three aren't bad. Keep the car on the ground. You need to remove the two 10mm nuts that are holding the wiring bundle brace to the fireweall. The top one is fairly easy to get to, just a small ratchet and 10mm socket. The bottom one is hard to find since it is not directly under the top one. It is closer to the driver's side and just over the ridge of the motor mount. Be patient with it and you'll get it off. The cruel bastards at Mazda also used a serrated nut so it never gets easy enough to just spin off with your finger. Needless to say you won't be putting that back on later.
The wire bundle will be a major pain in the ass. I couldn't find a good way to tie it out of the way, I just had to use one hand to pull it away from the firewall to get the sockets on the 3mm nuts holding the mount to the sub frame.
You only need about 16" of extension to get to them, and I was able to get them with U joint, a deep 17mm socket, all in 3/8".
Now the main longitudinal bolt is a different story. This is where good tools come in handy.
Get the car in the air and remove both front wheels and support the engine with a wood block and jack either under the tranny or oil pan. On the driver's side I used 2' of 3/8" extensions, a u-joint, a 17mm short socket, and a 18" breaker bar strategically wedged against the brake caliper.
The reason you need a bar on that side is because otherwise you just end up twisting the rubber of the mount and then just spinning the bolt without removing the nut.
On the passenger is where you want to do your twisting. Do not use 3/8" tools here. I sheered my friend's 3/8" u-joint in half, and one half is permanently in his 10" extension, so that's $15 in tools gone forever.
You want to go buy 3 10" 1/2" extensions and one 6", a 1/2" u-joint, and a 2" breaker bar, and a deep 6 point 17mm socket (impact if you have it). All these tools and rubber mount make for a fair amount of slack, so you have to just keep applying increasing pressure until it gives. Be careful to not fly into your fender or anything else when it finally breaks free. I have a 200ft lb electric impact that did not budge it, and I tried an 18" ratcheting breaker bar that was rated at 375ft-lbs that is now no more. So expect it to be pretty damn hard.
After the initial crack, the nut should spin off pretty easily. Then you can use a ratchet or metal object of choice from under the car to tap out the long bolt.
Getting the mount out of the car is a little difficult, especially since now the car is in the air. I just put a bunch of towels down on the front rail and climbed up into the bay. I ended up lifting the mount from the rear of the car to get it off the three studs first and then wiggling it out of the bracket.
Without the inserts in it, the new mount went back in much easier. Getting the nuts back on the three studs was a pain with that wiring bundle constantly wanting to be in your way, but come around from the intake side with your right arm and get them started with your hand and it should be fine. That reminds me, I removed my intake to come around to the motor mount from the side. The throttle body makes coming from the top very painful, it is sharp.
Feel free to PM me if you need anything explained in more detail.
