How? Practice ...
It depends on the wave shape, the ski stability, and your technique. Once you get in an unstable enough ski paddling parallel to steep enough wind chop, you will be destabilized enough that if you do nothing, you will fall off. This point comes early for new paddlers, later for more experienced ones with better balance. A more stable boat also lets you handle more side chop without the need to brace or waste part of your stroke on stability. But, you always reach this point of instability, no matter what, if you paddle in interesting conditions. This is the point where you have to do something or you flip. Here, your bracing ability will help you - if you can have power to spare and use some of it as a bracing component in your forward stroke, you will appear to the untrained eye from the side that you are just paddling. In reality, part of your effort will be to stabilize yourself with your stroke.
The previous gen V10 Sport felt great to me downwind, while across the same waves I felt unstable. I did not fall often from it, but I slowed down a lot. Practice improved that, but I never mastered it enough to enjoy it sideways in steep wind chop with white caps. A more stable ski or kayak makes it better.
I just try to take opportunities to paddle parallel to waves when I get a chance. Or go paddle in river currents (mild white water) with the ski. The unpredictability of moving water (waves and currents) are a good balance aid.
A class/lesson might help you develop your bracing stroke quicker.
I'm still ways off from being comfortable in side chop on my new Epic V10, so I just grab the Think Eze for days when I anticipate rougher conditions with short period steep wind waves - might as well enjoy the chop rather than struggle in it with the longer and less stable ski