I wouldn't just because I did it once and the paste (CLU) dried up somehow into a white powder crud. I moved my computer around a lot so it probably shifted the lid. The Lid is retained, its just clamped down with the lever arm but floats on the thermal paste above the silicon.
However since you are really into this, go for it. It will reduce your temperatures, always does atleast 5-10*C, some get 25*C or more.
Use the hammer, vice, wood block method. Thats how I did it and it worked fine. I tested it on 4 celerons that were $5 shipped each off ebay, and then did the i5 with it. I did two with a razor blade and it sucked. The hammer worked every time, took about 1 minute per chip. Razor blade took about 30 minutes per chip. Put electrical tape or something on the edge of the PCB so you dont damage it from the process. Clamp the lid in the vise, put some electrical tape around the pcb edge so it has some protection and start tapping it.
Use Cool Lab Ultra if you want the best result, the Pro stuff is harder to spread. Visually, it is more like a bubble of mercury (or in this case, gallium) than thermal paste, the CLU is closer to traditional thermal paste in that it is atleast somewhat paste.
I found that using more rather than less is the way to go. I read the opposite, but I think thats because most people are accustomed to excess thermal pasting and my idea of using more is still less than most people. Get the die and the edges coated in paste. Also paint a bit onto the contact point underside of lid. Really very similar to doing an graphics card.
Removing the remaining black adhesive crud on the lid and the PCB is imperative for cooler temps as well. Rub it off with a finger until it goes away.