usage: protogen -i:{infile2} [-i:{infile2}] [-o:{outfile}] [-t:{template}] [-p:{prop}[=value]] [-q] [-d]

-i: Input file(s); proto definitions, either as text or pre-compiled binary (via protoc)
-o: Output file; if none specified, writes to stdout
-t: Template to use; defaults to csharp
-p: Property for the template; value defaults to true; use -p:help to view available options
-q: Quiet; suppresses header
-d: Include all dependencies of the input files in the set so the set is self-contained.
-ns: Default namespace; used in code generation when no package is specified

Examples:

protogen -i:input.proto -o:output.cs
protogen -i:input.proto -o:output.xml -t:xml
protogen -i:input.proto -o:output.cs -p:datacontract -q
protogen -i:input.proto -o:output.cs -p:observable=true