I tried to use a compiler like gfortran to run mohid but I had problems with missed libraries,
and also I decided to install windows on my mac to benefit from the interfaces used in mohid, like mohid GUI, MOHID post processor and mohid GIS, which are really useful.
In my opinion the best solution is to partition the hard disk.
I have a Mac with Tiger 10.4 and I used Bootcamp to partitionate the hard disk. Note that Bootcamp is expired for Tiger so before to install it I changed the date of my OS to sometime before October 2007
(date of expiring Bootcamp and birth of Leopard).
But I needed Bootcamp only because it is easy tool to partitionate the hard disk.
I manage the double boot using REFIt.
http://refit.sourceforge.net/
I have an hard disk 130 GB and I dedicate 50 GB of disk to Windows.
I found this the best solution because I tried to use a virtual machine like Parallel desktop, that is very good, but sometimes crashes on my Mac. Also, by partitioning the hard disk and installing Windows on one of the two partitions, I have no limits in the use of the RAM under windows.
Best,
Isabella