Six steps to installing a C# compiler on OS X 10.3, using Rotor.
1. Download the SSCLI from Microsoft
wget http://download.microsoft.com/download/.netframesdk/CLI3/1.0/WXP/EN-US/sscli_20021101.tgz tar xfz sscli_20021101.tgz cd sscli
2. Download the patches for Panther in the same directory
wget http://www.mondrian-script.org/rotor/panther_mark2_diffs.txt.gz gunzip panther_mark2_diffs.txt.gz
3. Apply the patches
patch -p1 < panther_mark2_diffs.txt
4. Set environment variables
source env.csh (CSH or TCSH) source env.sh (BASH)
4. Compile (took just over an hour for me)
./buildall
5. Set environment variables again (I'm not sure why I had to do this)
source env.csh (CSH or TCSH) source env.sh (BASH)
6. Try the samples
cd samples/hello csc hello.cs clix hello.exe
7. Read readfirst.html in the root of your installation
I haven't tried installing Mono or Portable .NET on Panther; do let me know if you have.
Mono: http://www.go-mono.com/
Portable .NET: http://www.gnu.org/projects/dotgnu/pnet.html
Microsoft SSCLI: http://msdn.microsoft.com/net/sscli/