Installation can be as simple as following the installation wizard on a single desktop, or as flexible as "push" and "pull" delivery options with transforms.
To modify the basic installer process, you must have a competent grasp of how to create transforms, and an authoring tool to do so, and/or are familiar with command line options.
You should already know what kind of installation you need and should already have gathered the information required. If not, see Things to consider before installation.