As long as it's not "frozen", just set it on the fastest feed settings, engage the half nuts, and lock the carriage. That's all I've ever needed. Don' go yarning on it that way, but it shouldn't be "that" tight.
When you put the nuts back on, all they need is just a little "snug". Just having the gear train engaged is more than enough, no need to engage anything but the spindle. You don't even need the belt tight on the spindle. Just bring the nut up till it touches, then a light bump to snug it up.