WARNING: This page is about a different car, the 2004 Volkswagen R32. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Pressing On 3rd, 4th And 6th Gear
Courtesy of VOLKSWAGEN UNITED STATES, INC.
Heat gear wheel to approx. 100 ° C.
Press gear wheel on quickly so that heat is not also transferred onto input shaft.