Albeit mrViewer uses AMPAS' Color Transform Language (CTL) for doing its color corrections and table look ups, mrViewer also supports ICC profiles.
mrViewer's preference section determines whether mrViewer will prefer CTL or ICC when both are used in the monitor or in an image.One ICC transform is attached to the main view window and represents the monitor, video or film stock. This transform is set in the main preferences window, in the CTL section. Most projects will require users to set the device transform only once and not change it and it is recommended you use the MRV_ODT_ICC_PROFILE environment variable.
Each image can support its own ICC profile. For that, you need to add an ICC profile with the RMB. There's an option called Image->Attach ICC Profile, which does the obvious.
Once ICC profiles are loaded, you can examine their contents in the ICC profile window.
In summary, if you are new to color calibration, you should stick with CTL which offers faster feedback.