Mapping for a type?

Hi all,
I have an index, htldb, and it has two types, facebook and twitter.
I want to change twitter's mapping, as I learn from there:

I must change mapping of htldb, and reindex facebook and twitter.

Im curious about that, is there any way to implement a alias for types. so, I just create a new type twitter_v2 and get all data from the old one, twitter then remove twitter. At the end I set an alias named "twitter" to twitter_v2, so I can reach twitter_v2 with twitter type name.

Before writing this post, I searched it on the forum, and I found this:

kimchy recommended to create new indices for each type. It is reasonable,but as he mentioned, it costs me extra spaces.
Sorry about the word salad, my question is the solution,recomended above still valid one? is there a new way to create alias for types?