1. A method of installing a computer program, divided into a plurality of packages in modular manner, the packages representing in their entirety the complete computer program and being individually selectable by a user when installing the computer program on a computer system in order to create a customized computer program, the packages being sorted hierarchically, with packages ranking higher in the hierarchy being dependent on and dominating packages ranking lower in the hierarchy, the method comprising: defining a graphical user interface representation of a profile of functions required to be performed by the computer program to be installed; providing rules of dominance relating to the ranks of the packages among each other, wherein the rules of dominance apply in case the package selection by the user results in a conflict of the content of at least two of the packages, the rules of dominance further indicating that a package with a higher rank in the hierarchy that is dependent on a package with a lower rank in the hierarchy dominates the package with the lower rank and, therefore, modifies settings of the lower package to solve any conflict of the content of the at least two of the packages; selecting a first package from the plurality of packages, the first package being a core package of the computer program to be installed, containing basic functions of the computer program to be installed, and representing an independent functional subunit of the computer program to be installed; subsequently selecting, on the basis of the first package, a second package from the plurality of packages, the second package providing computer program functions building up on the selected first package while observing the provided rules of dominance; comparing the functions of the selected first and second packages to the graphical user interface representation of the profile of functions; applying at least one of the rules of dominance when there is a conflict in content between the selected first package and the selected second package; and subsequently selecting additional packages from the plurality of packages until the functions of the selected packages fit within or exceed the defined graphical user interface representation of the profile of functions, wherein the exceeded functions of the selected packages are de-installed in order to reproduce a finely matched profile of functions as the defined graphical user interface representation of the profile of functions.