On another forum I discovered a script that should automatically fetch nzb-files bookmarked on newzbin site.
If you interested here is a link.
Thanks go to member bluebeer, the author of the script.
Since I do not have a newzbin account I didn't tested the script.
If you want to use it on optware platform be aware that the default "wget", which is a part of busybox executable, does not support option "--post-data" and ssl-connections. To get a fully featured "wget" install package "wget-ssl" with "ipkg install wget-ssl".