openconnect and authenticating proxy via script

[Jeffrey May]

If calling the openconnect client from a script, and you specify an authenticating proxy (via −P,−−proxy proxyurl), how do you provide the authentication credentials?  We are using a very lightweight Linux (Microcore), without niceties like GNOME NetworkManager, within a VirtualBox virtual machine.  

If this is not currently supported, I would think a mechanism like --passwd-on-stdin but for proxy would be feasible.  Perhaps a way to pass in multiple sensitive key-value pairs via a pipe (e.g. echo "vpnserver:my.vpn.com;vpnuid:test;vpnpwd:testpwd;proxyserver;www.myproxy.com;proxyuid:me;proxypwd:mepwd" | openconnect -b --config-on-stdin)?  Not pretty, but flexible.

Thanks