Not sure what you think he was saying but all he is asking is whether you can install rev 20b using a base of IOS 57 v5919 instead of the typical v5918! The answer to which is I don't think it makes any difference (we are taking base not the originating trucha bugged IOS or cIOS used to do the install).Sao Mortel said:No!
A cios is a modified ios. That is why its illegal because its nintendo code thats been changed.
Unless you modifie it yourself youll have to stick what devs (waninkoko and hermes )give you.