Assuming you have not MINIX running, read
http://wiki.minix3.org/en/DevelopersGuide/UsingGit as a "community
member" and discard any remark about "pkgin" or anything MINIX-specific.
And yes, you need git installed on your machine to do that.
The alternative path only works with Linux and is not supported AFAIK:
download the .iso, use fdisk(1) or some MBR partitioning program on it
to learn where the 3rd partition starts, then virtually mount that
partition (i.e. with offset) as minixfs: the source code is at /mnt/src.
I guess you'll prefer the git way. ;-)
Antoine
There is yet another alternative; download a git snapshot from the git
webinterface http://git.minix3.org/?p=minix.git;a=summary. You'll get a
.tgz file of the complete source tree of any given commit.
--
Thomas