Perhaps I misunderstood the question? labmaster, did you want to add a new item to you enum? Modify an existing item in your enum? Or just programatically select which existing item in your enum is used?
If it is the last option that you are asking, you can write to the 'value' property of your enum or write to a local variable of it.
If not, then I agree with previous posts, you shouldn't programmatically change your type def's. You should look for an alternative way to achieve the functionality you desire.
Troy - CLD
"If a hammer is the only tool you have, everything starts to look like a nail." ~ Maslow/Kaplan - Law of the instrument