Highly accurate localization technologies are a key enabler of future intelligent transport system applications including automated and cooperative driving as well as location based services. One major challenge is positioning in urban areas, where high buildings with reflecting surfaces lead to signal blockage, multipath effects and Non-Line-of-Sight (NLOS) reception. As a countermeasure, deterministic NLOS modelling approaches using 3D map aided GNSS (3DMA-GNSS) have been developed and show promising results in mitigating those effects. However, most prior studies focused on advancing the method itself, while the implementational aspects of such a system regarding real-world applications remain unsolved. Major challenges lie within the generation and dissemination of suitable 3D maps as well as the computational cost of the classification of measurements into LOS resp. NLOS behaviour. The aim of this paper is to connect the parts of highly precise GNSS based urban localization, digital maps, Vehicle-to-Everything (V2X) based cooperative positioning and data dissemination. A map dissemination scheme for precomputed sky occupancy masks using V2X communication technology is evolved and discussed. Furthermore, the data rate requirements are compared with the capability of the existing IEEE802.11p (ITS-G5) V2X standard in terms of data rate and the range of the communication link.