Check of environment variable http_proxy
can provide an automatically setting of a proxy in genkit.
So the build will work with a proxy host straight forward
without any changes.
genkit workaround after genkit download:
mv genkit genkit.orig
awk '/package require http/{$0=$0"\nif {[info exists ::env(http_proxy)]}
{\nregexp {//(.*):(.*)} $::env(http_proxy) m h p\nhttp::config
-proxyhost $h -proxyport $p\n}"}$0' \
genkit.orig >genkit

Great, I've added your change change to genkit. Thanks - much appreciated!