I'm not sure exactly what kind of information you're looking for, but it may be useful to contact an engineering company dealing with design of hulls for floating units - jackups or semisubs.

One that I know of is this:
http://www.mscoffshore.nl/engineering/engineering.html

They have wide experience with hull design and related stability control (calculations)

Hope this helps
regards
Mogens

You might try ABS site (American Bureau of Shipping). You can download many of their sets of Rules. In particular the Rules for the Design and Construction of MODUS (Mobile Offshore Drilling Units)will give you a lot of information on ballast and stability. These Rules are specific to 'Column stabilised units' (semi-subs) and 'Self Elevating Units' (Jack-ups). Most of the world's MODUS are classed by ABS so they have a wealth of experience. There are also other Rules & Guidance on ballasting on the ABS site

Thanks for your suggestions.  Since the original post I have become familiar with some of the applicable ABS rules and the GVA Sea-Loc (tm) ballast scheme for semi-submersible vessels with a square pontoon and four columns.

John