Your Pacer does trot and canter properly... for a Pacer! I have known people who have trained them to have the paces of a riding horses. However, to achieve this is as difficult as training a riding horse to pace. From what I have seen, it is a lot of work and the results are at best mediocre. In the sae time you could train a warmblood up to affiliated level & achieve something.
The people I know who have done it re-broke the horses and conciderd each diaganal separately, right from the start. When you are riding the horse you are telling each leg what to do independently. So, riding them is very 'involved' you have to think collection, outline, up to the bit, leg, 1, 2, 3, 4, forwards! You can nopt relax or they revert to type.
It is possible, but you have to ask whats the point. If you want a horse that paces, buy a pacer, if you want one with traditional riding gaits... buy a riding horse.
Rather than banging your head against a brick wall, get him harnessed up & drive him, you will have much more fun.