Where you put the pier will depend on a number of things and what is good for some may not suit you.
The first thing to know is your latitude. This will determine the fine location of the fulcrum about which your rotational tracking will rotate.
In a Fork mounted telescope this will be the centre of the axis of declination. This needs to be at the centre of your dome and the pier will usulally need to be offset to accomodate this.
On a GEM the center of rotation will be the basically the same position. The point where the declination axis and OTA Axis intersect along the centre line of the RA Axis
If you have a heavy scope that needs to be mounted equatorially allow for a crane of some sort to plumb this centre.
This is my design for a Sirius 2.3 metre dome
http://barry.sarcasmogerdes.com/obse...s/obsvatry.doc
Barry