Martha Armstrong-Hand used spring tensioning to assemble her porcelain BJDs. Most of the porcelain BJD makers that I have seen, also use spring tensioning. This tutorial gives an idea of what is involved when spring tensioning a porcelain BJD.
How to put a Ball Jointed Doll BJD together by Cindy McClure.
The construction and engineering of the inner workings of a BJD will consist of:
1.dowel pins epoxied into each joint of your BJD.
2. Line each joint with leather (soft side glued to the porcelain, shiny side of leather out, very important)
3. Assemble your springs, swivels, and s-hooks.
The size and tension of your springs are key.
I am planning on stringing Aalish with 3mm round doll elastic cord. I will see how it works. Who knows, I may end up using some sort of spring tensioning with Aalish?