Even though this is probalby realy bad thung to do, here is some code that'll get you close. It will pad a leading zero to single digit months. So, if you need to remove that you'll have to add a little more code to remove that.
DECLARE @Foo TABLE(Val VARCHAR(20))
SET Val = CONVERT(VARCHAR(8), CONVERT(DATETIME, Val, 101), 1)
FROM @FooEDIT: cut-n-past error.