You can google around and watch some vids out there. Recently installed on my gtx155 '15. It'll take you some time but you can do it. No special tools needed. The depth finder took the longest and the biggest pain was getting the wire connectors in the fuse box.
That was one of our first videos. Unfortunately, I didn't quite finish it before the battery ran out, but it should be useful to you ... https://youtu.be/xOm8IzCt1XY
Good luck.