You can but you won't flat cut it anymore, you'll be adjusting your saw twice for every cut. I suggest you go rent a saw and avoid yourself a lot of frustration.

You can hold it against the fence as it was the corner between the ceiling and wall, and just use the regular miter https://i.imgur.com/loT2eAg.jpg

If I stayed with this saw and the flat cut method, how would I do the second cut without the second bevel? Flip the board over?

You would cut your length and angle with the first cut flat then you'd cut the back bevel cut on the crown against the fence so the miter joint is tight. Sounds easy but depending on your crown profile this could be rather difficult to achieve. Just an fyi

For inside corners, one end of the crown is cut square and butts against the wall. The other end is cut mitered for an inside corner first and then coped. The process for measuring remains the same.

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But, unless the crown is too big to cut "standing up" like shown in the picture linked above there's no reason to cut it flat. The picture linked above shows how to cut crown "upside down and backwards" for lack of a better way to describe it.

Got it… I see what you’re saying. I just tried the other methods… having the board top-down at a 45 degree angle against the back fence and cutting on a 45 degree angle. Worked fine for both inside and outside corners so I’ll thick with that method. Thanks for the insight.

Not a problem. Good luck!

If your sawblade is big enough.... make a fixture to hold the crown upside down and backwards against the fence.(the base of the mitersaw is the ceiling, the fence is the wall)

Then just cut 45s.

The easiest way to cut crown under 3-1/2”. Put the crown on the miter saw upside down from the way it should be installed. Scribe a pencil line top and bottom on the table and fence of the saw. Now, you can just cut 45° miters for inside and outside corners. Just hold your crown on those marks for the next cuts.

When installing crown. I always shoot the crown 18” or 24” from the corner. If there’s a small gap at the bottom push the trim upwards. Opposite for gap at the top.

I just went through this. At first I was really intimidated by holding the crown upside down and having to cut everything backwards. After a few pieces, I got the hang of it. In my opinion for a homeowner its not worth it to have a double bevel saw. one thing that really helped me was making a jig to hold the crown in the same place every time or else the cuts won't line up properly. You can also buy crown stops if they're available for your saw.

This is the best answer so far.

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Follow the same process of marking the wall and ceiling every few feet to make sure the crown doesn't roll on you and viola.

This is how I did it when I installed kitchens. It can be tough to hold the crown steady again the fence so you can get an attachment for the saw called a crown stop that holds the top edge(which would be against the base of the saw-upside down) steadily to keep the cuts consistent

Personally I just cut out a few triangles and used them as support between the molding and fence. Worked great!

But OP do a few tiny test pieces first so you can make sure the molding is cut the right way. It's been a while since I did this so I might be misremembering, but I think it needs to be upside down so the top of the "bottom" of your molding is against the fence?

That'll work much better than just having the piece against the fence for sure. And yes you do need to have the piece upside down, makes it so much easier to see where your mitres need to end up