I can interpret it in two ways,
I think, the ACS Redirect Manager helps us to manage redirects at the Apache level, but I see that
you are expecting to store redirect configurations at etc/map level, seems like you want to configure internal redirects.
If that is the case, then you need to write a custom logic
1. You can reuse ACS redirect manager interface, check the below link for reference page
https://github.com/Adobe-Consulting-Services/acs-aem-commons/blob/05e6e86fb69aff6afe7c3e4297b2be1d787e268a/ui.apps/src/main/content/jcr_root/apps/acs-commons/components/utilities/redirectmappage/content.jsp
2. On submit button click, you can call servlet and check whether mapping entries exist under etc/map, if does not exist then create a new one using Node API
If the requirement is not storing under etc/map then you need to do analysis or do simple POC whether ACS redirect manager is meeting all your requirements or not, if not then you need to do reverse engineering.