I assume you are talking about a monitor profile. But ICC profiles can be for printers, scanners and other input/output devices.
Even within the same model, displays have varying color characteristics. Ambient light also alters the perception of color. As monitors age, backlit illumination fades, which of course affects color. Because of all these reasons, it is best to purchase a calibration device and generate your own profile. Depending on how critical, you may wish to recreate it on a weekly, or monthly basis. Starting from scratch is not such a bad thing. Apple allows users to select a default display or visually calibrate/create a new one. It doesn't take long. However, it is not as accurate as creating one with a device that measures the chromatic value of displayed color patches.
There are too many variables to manipulate by hand. Some type of third party software is required for visual feedback. Apple provides a very basic ColorSync Utility in the Utility folder. It can list and repair color profiles, establish global default profiles, alter profiles within documents, and upload default RGB conversion for CMYK printers. Unfortunately, there is no visual feedback for any of these options. As you would expect from working in the dark, you can wind up causing more harm than good. Read the Help with the software before performing any changes.
On my network I have various Xerox and HP printers. One of the latter came with the HP Advanced Profiling Solution. The software/hardware combo cost $500 separately but provides an interface for creating and editing ICC profiles for printers and displays. Designed to work only with the newest HP wide-format printers, it can edit ICC profiles for other networked printers, including Xerox. Printer calibration is dependent upon paper used.
If you are borrowing other people's profiles, I doubt you are ready to invest in expensive profile editing solutions. My best advice would be to purchase the EyeOne LT ($140), Pantone Huey Pro ($99), or original Pantone Huey ($63) and generate your own profiles so you won't have to get into the details of editing. All these calibrators (and more expensive ones) are available from Amazon.com.
