Generic solutions don't always work.
What CRT do you have?
Are you keeping it in a case?
This will make a difference.
If you are going VGA monitor in case, just build a shelf at the angle you want... Then remove the bottom stand from the monitor... Then Build a flat shelf to sit it on... Get it in the right area... Then screw in some wood to make it not move. Then if you get a different monitor later because of... well... Whatever... You remove two small boards and you should be fine.
If its out of case... Then you need to find out how you CAN attach it. If you have room, it might be better to build a small frame around the CRT itself... then attach that to the cabinet.