在更改列数据类型时保存SQL索引

I have a smalldatetime column that I need to alter to be a datetime column. This is something that will be part of an install process, so it cannot be a manual procedure. Unfortunately, the column has a few indexes and a not null constraint on it. The indexes are performance related and would need to be retained only using the new data type. Is it possible to write a statement that will allow me to retain the relevant information while still altering the column datatype? If so, how can this be done? I have a smalldatetime column that I need to al