Problem: It's not possible. There is not place to type an URL in winscp.
1. You are forced to use a Login screen that makes you manually type everything in separate boxes. So you have to copy and paste from your URL: server name in server box, directory in options, user in user, pass in pass, etc.
- Solution: Show a bar to input a full URL at Login screen / site manager, and make winscp auto fill everyting for you.
2. Command line only accepts "winscp-ftp://" URL format, not "ftp://"
- Solution: It could also accept a normal ftp URL, but check point 3 solution.
3. There is no place to type an URL in the main screen
Solution: Show an optional main screen URL bar.
Extra: Do not force the Login screen at beginning, if there is an URL bar or the command line also works as URL bar there is no need to close and skip that screen every time.