I just went through this with my Taig.
I will describe how and where I mounted mine but I'll try to post some pictures soon.
First off my general feeling is that I don't like to drill holes or other wise modify my machine, at least not until I am certain what I am doing will work as expected.
I also prefer my switches to be stationary. I used the same sealed lever roller switches in all positions. I used 1/8 Alum plate and angle for all the brackets.
I installed my X limit/home switch in on the frame where that little center post is located...I just unscrewed the retaining bolt and pulled the post as it serves no real
good purpose. I then built an L shaped bracket that is retained by using a 10-32 bolt into the original retaining bolt hole. My eventual plan will be to make a bracket the mounts in the hole where the original post was but I haven't gotten to that yet. With the switch located in the center I then created 2 ramps that I mounted to the front of the X table in the slot that runs the length of the edge of the table.
For the Y movements I used two switches one mounted in front using another bracket that bolts to the black Aluminum plate that retains the lead screw....for this I just used the original retaining bolts and cut my bracket to clear the lead screw and mounted it on the outside. As the table runs out from the column is runs over the roller switch to trip the limit. In back I made another plate that I drilled with a 1/2 inch hole an slipped over the big bolt that holds the column in place then put another nut on that bolt...the bolt was plenty long to do this but it means a bit more effort when tramming the mill. To this plate I mounted another small piece of angle with a that carries the switch and holds it in position so when the table comes back it again slides over the roller and trips the switch. I may try a couple of thinner jam nuts in the future and see if I can get it so I can tram the mill without removing the plate but it is not a big deal either way.
Lastly I placed the Z switch at the top of the mill retained again but the two screws that hold the the mounting bracket for the motor. In this case I replaced the original screws with ones that were 1/2 inch longer so that when tight the protrude out the back of the mill enough to mount the switch plate and put on a couple of nuts. this plate holds the switch so that the carrier for the head stock closes the switch just before the mill reaches the top of it's movement. This is the one switch I have a slight problem with as if I push the motor past the switch point it will jam the switch in a limit exceeded position but then you should not do that and it fails in the tripped position.
I haven't found a good or meaning full way to mount a lower Z limit. I am not sure it will really mean anything unless you have a certain maximum tool length. It is however in some ways the most important switch as it is the one that would prevent you from running the mill into the table or preventing the head stock from dropping totally off the lead scew (I am not sure about if that actually happening) but when something went haywire with my controller/positioning I did cut a nice divot in the table.