In order to become an SDN scripter you would need to make an SDN request. Upon making this request @Alek will take a look and judge whether the script should be placed on the SDN based on the type of script and whether or not it contains malicious code.
As for official scripter, following the demotion of the recent script manager and now that the SDN is back in the right hands this rank isn't available anymore through application. You would need to have an SDN script, and in addition Alek will hand pick you if he sees you fit for the title.
Hope that clears things up