Hey! .
First of all, it is possible, not easy but possible.
Now the reason why you are told it is not possible is because they are fused together. Fused together basically means that LCD and Digitizer is glued together. There are other devices out there on the market that does the same thing ( Samsung ). So the reason why repair centers say they cant do it ( including the one I'm working in) is because it is really really REALLY HARD. The reason for it for being hard is because you have to heat the digitizer up so you can separate it from the LCD.
The easiest route to go on this is to buy an assembly set from either ebay or Amazon.
When it comes to the guide, simply heat up the edges of the screen take the screen off just like you would on an ipad air. Be careful in the button right hand corner because your connectors are down there and you dont want to rip the connectors apart. so tilt the screen out, take the screws out replace the screen and BUM BUM new screen.