Noel,
Unfortunately, I don't think that the alter statement (either for the
data or for the index) will help much. The standard engine will not
reduce the size of the file unless the table is dropped and rebuilt. On
the positive side, if you anticipate that the file will grow again, the
space is already allocated, so it won't get bigger until it has reached
its current size.
Probably not what you wanted to hear, but I think that the import/export
is the only way to go...
-- Dan