If you are just printing with existing profiles then there is a check box for advanced options, and when that is clicked there is a slider labeled "ink limit". lowering that slider will lower the total amount of ink for the currently selected curve(s). This is different than the ink limits for each channel that are set in the ink descriptor file.
Hope that doesn't confuse things further. It wasn't exactly clear where you are starting from and where you are trying to go with this.
Richard Boutwell
http://www.richardboutwell.com/