Plugin getting username/password?

Is it possible for a plugin to pull the username / password used to login to Spark? I need to have a plugin authenticate with another server using the same credentials as the client is already using, so rather than having the user enter the same data twice, it would be nice to just pull the user/pass into my plugin.

Anyone have any thoughts on how to do this? I’m willing to modify the spark source and run a custom build if needed.