I'm not part of the blockcert team and I just had a quick look at the cert-issuer module. When you call
cert-issuer it'll run
__main__.py and you can trace the chain of the function run from there. The console command options are mostly (if not all) stored in
config.py. Parts that need 'Bitcoin' usually have an
import bitcoin or
from bitcoin import * on top and these are generally the files you need to add support for Ethereum.
The current implementation is quite tied to Bitcoin so I think if we want to add support for Ethereum (and make it easier for other blockchains) we might need to abstract out some components. I hope that helps a bit I'm sure Kim will have better answer when she has the time to reply. All the best!