I have to ask: Why do you want to do this?
If you insist on confusing your readers by having all the symbols in an effectively random order, you will probably have to specify that order yourself. For example,
Code: Select all
\nomenclature[1]{$\gamma$}{Surface tension}%
[text]
\nomenclature[2]{$\kappa$}{Compressibility}%
[more text]
[etc.]
Makeindex (which nomencl uses) is designed for the express purpose of alphabetizing things; what you're doing is effectively making a table of symbols in a specific order, which isn't really an index at all. You might be better served in the long run by simply making your own list environment and typing it explicitly.