How to implement Ctrl & alt keys in code

Hi All,
Im writting scripts for some gui elements such as complex gradient fills.
Using these for example:
Red... a series of 4 different red gradient fill scripts attached to 4 seperate buttons .
Green... a series of 4 different green gradient fill scripts attached to 4 seperate buttons .
Blue, Gold, Orange and lots more. each the same but with different colors.
This all works well but starts to crowd the gui. So I was wondering how to make it so, when a particular button- red for example - was pushed, holding down the CTRL key or ALT key or Shift etc. or combinations of all would effect which script runs.
I hope thats not too confusing
best regards
Andy