The gRPC server is based on a fork of BCHD. The source code is available on Github
git clone https://github.com/Fabcien/bchd
git checkout ecash
cd bchd
go build
./bchd --txindex --addrindex --slpindex --slpgraphsearch --grpclisten=0.0.0.0
More documentation is available in the Github repository.
A public gRPC server instance is available at grpc.fabien.cash:8335
Documentation for building a gRPC client can be found here