The real issue is that Blogger doesn't give you a way to set custom URL's for your pages. I was fairly frustrated with this for a while, but I figured out that it is actually very simple. I realized that it is directly connected to the title of the page. If you type in the title you want for the page it will set the first few words of the title as the URL:
So, all you have to do is to publish the page with your title as the custom character combination and that will be in the URL:
Then you can change the title to what you want it to be:
The key is that you must publish it with the custom character combination first. Then that will be the URL for the page until the end of time. Even if you revert the page to a draft, when you republish it, it will have the original title in the custom URL. Comment below if you have any questions or if you have an easier way to do this.