Hi Willem,
Luckily, you don’t need to factor the amsl numbers into training as far as adjusting weekly vert gain. The ME durations/prescriptions in the plan remain the same irrespective of the height you plan to climb at. You don’t need to apply any factors to vertical gain per workout on account of the height you plan to do the climbing. Simply put, building a big aerobic base and doing some specific ME is what helps climbers at altitude. Outside of training, stuff like acclimatization tactics and expedition hygiene are very importance as well.
Happy training.
-Seth