This should be self explanatory, let me know if it isn't.
btw: i drilled out the 10-32 screws and replaced them with 1/4-20.
the steel is some mystery 3/4" thin wall pipe, pretty lightweight but sufficiently strong.
You're going to gain at least a solid inch of travel before the Y axis slide comes too far off the machine.
Also why the heck did Taig not go with the tapered X axis gibb (sp?) design for the Y axis? they used it for the z axis as well...
another mod to gain another half inch is to take the entire Y axis aluminum plate and the two steel ways.. and move that about half an inch further away from the back of the machine, you will then be able to send the y axis off the end of the ways away from the operator. (but you'll have to drill and tap 8 more holes.)