I would also like to chip in that I'm also struggling to get this to work, which is quite a problem for me on a few sites. Still a great plugin I just need to get this functionality working.
Im using WP 3.5.1 and version 0.9.2.11, Using Disc:Basic & also Use late "init".
Have tried different combinations of mfunc code, as I'm sure everybody else has, but the output still gets cached.