This is going to be pretty darn difficult. You will likely have constant hunger.If you go two or three days on juice or water you will lose physical hunger making the fasting much much easier.

You are better to do a continuous juice fast if you can't do water. Or mix up juice and water but wouldn't have solid food at all during the fast.
Another option is warrior type intermittent rather than every other day fasting or FAST -5 .In warrior you pretty much eat once a day although think he also said eating very light few times like piece of fruit in morning and soup or very light salad at lunch was maybe ok too. In fast 5 you only eat in a window like 3 to 8pm type of thing. At least with these you are eating every day so maybe not as bad for hunger as complete alternate day fasting.
But of course if alternate day works for you then do it.

All are variations.You can also build to it by starting off skipping breakfast for week,then skipping lunch just eating supper. Lots of ways to do this.

Hello
I am starting tomorrow monday a 42 days juice fast and would be happy to share on this one!
xxx

I fast on and off. I think it's helping me eat better, and my skin is looking really great, my weight is going down, not as fast as someone fasting lots of days, but if you eat healthy in between fasting on and off, it works. I fasted a week once, the hunger didn't go away after 3 days, I was thinking about food constantly. So, this works better for me.