Thanks Carlos, I didn't know there was some commercial version of such a slide. Do you have a picture ?
I found it easier and more versatile to fit it on the tool rest post, and installing it on the bed would be more difficult because of the difference of height.
The platform can be used as a tool rest also, for some end grain works with flat tools. People making Chinese balls use such platforms for instance :
http://www.channelislandswoodturners...se_ball_01.jpg