Eurikain,

Listen to the sound of bearings moving in this video:

http://www.youtube.com/watch?v=bGbWBDtzydw

It sounds bad.
Very bad.
Very, very bad.

I'm guessing this video or something like it is where you got the idea for DIY supported rails.
It is a bad idea.
Very bad.
Very, very bad.

The reason why everyone is giving you negative feedback is because it is a bad idea, so ditch it and move on. If it helps any, hiwin rails from hobby machines have a good second hand market value. When you outgrow your machine you can recover a lot of the price by selling them on.

PS I'm the resident village idiot, annoying people with my hair-brained ideas, even I figured out that DIY supported rails was a non-starter.