Its simple (assumes developer tools, Xcode, is installed).
Download the current version (remind-03.00.22.tar.gz)
Open a Terminal window, cd the directory where the file is, and type:
% tar zxfv remind-03.00.22.tar.gz
cd to remind-03.00.22 and build
% ./configure
% make
% sudo make install
If you do not have root access you can install it locally by copying the remind and rem2ps binary to a local directory, say ~/bin, and adding the directory to your path.