The only real difficulty with installing vinyl railings on a concrete porch is that the railings are slightly more difficult to install in comparison to on top of a wood or composite deck. Since concrete is much harder than wood or composites, special tools and mounting protocols are needed, which are naturally more time consuming and more difficult. However, other than the extra time, installing vinyl railing on a concrete porch is no different than anywhere else.
The easiest way to streamline the installation process for your vinyl railings is to have some form of preparation done during the pouring phase of the concrete porch slab. This is where manufacturer-supplied mounting brackets are set into the concrete during its initial hardening phase, when it is beginning to harden but still pliable enough you can push something down into the slab. Once the concrete hardens, these protrusions can help aid in the mounting of the vinyl railing.
Another way of mounting vinyl railings to a concrete slab is to use the drilling method. You cannot nail vinyl down to concrete, as nailing into the slab is nearly impossible. Instead, special screws must be used that are specially designed to work with concrete. These may be included as part of the kit for installing the vinyl railings, or you may need to purchase them separately. Other than that, it is the same process as drilling into wood.
Although it is not always the first choice for installing vinyl railings, epoxy compounds can be used to stick the railings to the concrete. This is a less popular choice given the fact that with screws, for example, you can change the railing out later, but with epoxy the issue is that once it hardens it is there forever, much like the concrete. Epoxy is also difficult to work with, requiring skill and efficiency so you can quickly install the railings before the compound hardens.