I was very lucky with the Nathan Bridgewater blog scripts. You can check out the latest ones: Mono Install Scripts . They are quite easy to update the parameters of a parallel environment or mono version, if necessary.
You can also install from github (see section C) , but you will need to get XSP and something that is uncomfortable:
git clone git://github.com/mono/mono.git cd mono ./autogen.sh --prefix=/usr/local make make install
(select tag / tag after cloning if necessary)