In my opinion, the design of the package multicol does not allow this, and cannot allow this.
I can think of only one other option, and that is using the standard [twocolumn] class option or \twocolumn command. The true problem is then the column balancing on the last page. There are several possible solutions to this problem.
Manually balance the columns. This can be done by issuing the following commands in the first column of the last page (the value 0.2 has to be adjusted manually):
\raggedbottom\enlargethispage{-0.2\textheight}
Use the package cuted. The following commands ought to be added at the very end of the document. The only issue is that if the last page is almost full, an extra completely empty page might be created. The commands are:
\setlength{\stripsep}{-\baselineskip}\begin{strip}\end{strip}\leavevmode
Use the package balance. However, this package is not reliable and corrupts vertical spacing. The usage is simple: issue the command \balance in the first column of the last page.
Or of course, you can wait for the LaTeX3 team to finish the new output routine xor, but this can take some time.
flowframcan be of help here. See Three-columns text with figures of 2`\columnwidth` and How to write a title/abstract spanning 2 columns in 3-column page using multicol?. – Werner Dec 29 '12 at 18:09multicoltotwocolumn" a valid answer? – tohecz Jan 5 at 14:40\raggedbottom\enlargethispage{-0.2\textheight}, where you modify0.2to a value such that the output looks nice. The only real drawback of this method is when you have chapters because then you must do it for each chapter. But who has a twocolumn document with chapters? – tohecz Jan 5 at 18:29