when you first try it out, you will probably not be carving out switch. You will push some snow and then you'll be slide slipping switch. That is ok because you will learn. I kind of think of it as doing a carve and then carving switch done very rapidly
Notice that during your normal carve, there will be a change in pressure points during the turn so that you can maintain that carve. When you change directions on a board whether it is carving or side slipping you apply different levels of pressure to a different part of the board without thinking about it. So at least from my experience, the trickiest part is going from a normal carve directly into a carve in reverse which will require rapid change in where you apply weight/pressure in the board. When you first try it you may notice that after you go into the switch, that most of your weight/pressure is on your front (now back leg) after starting the switch. And if you want to be carving switch smoothly you will need to pressure your new front foot (which was your back leg before your started) more. So after you initiate your normal carve and are in the middle of a carve, you're going to have to suddenly apply more pressure to your back foot pointing downhill to initiate/maintain reverse carve.
And as the others have said you have to already be comfortable switch CARVING.