The method depends on what kind of permutations you want to do.
Given N objects in X different positions, do you want to allow repetitions? Do you want to include permutations with less than X values?
There are formulas available that will calculate these. Excel actually has some good statistical functions that not only do the calculations, but the help file does a good job of explaining the formula used. You might run a couple test on a spreadsheet until you are sure what kind of permutation you want, and then port the formula from Excel's help file into a TSQL statement.
If it's not practically useful, then it's practically useless.