I was wondering if it was possible to download a list of IP’s from a URL in text format like:
10.0.12.123
10.0.34.23
etc.
Then convert them all to a dynamic address list in a Mikrotik router.
Yep - through scripting
https://wiki.mikrotik.com/wiki/Manual:Scripting
Have also a look at this thread: http://forum.mikrotik.com/t/blacklist-filter-update-script/89817/1