how to upgrade MacPorts behind proxy?

[Richard Cobbe]

What's the best way to upgrade to MacPorts 2.3.0 on a computer that's
behind a proxy?  I'm currently running 2.2.1.

For normal package upgrades, I've got "port -d sync" working via SVN (as
per the instructions on
<https://trac.macports.org/wiki/howto/SyncingWithSVN>), but of course that
won't automatically update from 2.2.1 to 2.3.

Is it as simple as just downloading the new .pkg file and installing it on
top of the existing installation (and then running "port -d sync; port
upgrade outdated")?  Will the fact that the installer itself tries to run
"port selfupdate" cause problems when that fails because of the proxy?

If it matters, the computer is running MacOS 10.9.3 with XCode 5 -- I don't
have access to it right now to check the precise XCode version number, but
I've applied all available Apple updates.

Thanks,

Richard