For those of us who don't use Visual C#, the following Makefile seems to build the client quite happily. Not sure why the /nowarn is required though.

Code:
CSC=/cygdrive/c/WINDOWS/Microsoft.NET/Framework/v1.1.4322/csc.exe
OUT=myseq.exe
WARN=/warn:4 /nowarn:1591

SOURCE=AssemblyInfo.cs Form1.cs Form2.cs Form3.cs Form4.cs MapCon.cs MapPane.cs
ICON=/win32icon:App.ico

SWITCHES=/out:$(OUT) /target:exe $(ICON) /doc:myseq.doc $(WARN)

$(OUT):     $(SOURCE)
                 $(CSC) $(SWITCHES) $(SOURCE)

clean:
                 rm -f $(OUT)