I am not exactly sure where the issue is.
I would expect you could import dates in the DD-MMM-YY format into a DateTime Column without problems.
Once in a DateTime Column (or variable) you could use Convert to display in whichever format is necessary e.g.
Declare @MyDate DateTime
Select @MyDate = '15-Apr-09'
Print Convert(VarChar(10), @MyDate, 101)
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