Internal Temporary tables

[Marcello La placa]

Hello,
I have a question about the internal temporary tables which are created when ever ORDER BY or GROUP BY are used.
As far I understood the internal temporay tables are created initially in memory,but if the size id too big then it is converted in a on-disk table using the MyISAM engine.
Because I suppose that is the same whenever Innodb is used, I am wondering if doing some MyISAM settings will help to speed up the creation if those temporary tables whenever the statement ORDER BY or GROUP BY are using over a Innodb Database.

Thanks