vanitygen -r '^1[BDEGKLNRTUWXYaemuz12457]{16}'
In the above expression, "20" means it searches for a match for the first 16 characters only. That's less than Kostelooscoin wants, but at least this gives some result without waiting forever.
To get a better match, increase that number. Or allow more different characters, that'll greatly improve speed.
Another example:
This gets you a private key without lower case characters:
vanitygen -r '^1[123456789ABCDEFGHJKLMNPQRSTUVWXYZ]{33}'
You can also add "-k" to the options, and search for a bit less characters. This way you at least get to see some progress when searching for rare outputs.