Did you actually read my question?
Probably, but the contract "support engineers" here have a habit of providing answers to questions that haven't been asked. I really know nothing about Microsoft Math and thus can't provide a direct answer, but I think if you do a Google search for "Microsoft Mathmatics stepwise function" (no quotes) you'll see that it apparently can be done, after a fashion, and not very well. Sorry I couldn't offer more help, but maybe someone else will come along with a more definitive answer.