I have a build configuration which deploys my code to a machine. Depending on which machine I am deploying to (e.g. dev/uat/prod), I need to run as a different user.
Ra
The RunAs plugin combined with TeamCity 7's new Typed Parameters will let you make the password a "typed" parameter plugin.
Then, when it's entered at the Run screen, it will not be visible in the build history.
EDIT: Much later, as covered in the comments: You probably don't want to do this. Consider having separate pools which run as different users, and parameters to specify what builds are supported by what pools.
Neil, you can pass build parameters via Run Custom Build dialog.
There are "System properties" and "Environment variables" sections, where you can add new build parameters or redefine existing ones.
Please read more: http://confluence.jetbrains.net/display/TCD6/Triggering+a+Custom+Build