According to the current CSWIP document (CSWIP-WI-6-92 12th Edition May 2012), anyone who wishes to directly attend the CSWIP 3.2 course and exam under the mature route must hold an International Welding Inspector Standard Level Diploma with five years' continuous recent experience in senior welding inspection duties (Clause 1.4.3).
Another way to gain the CSWIP 3.2.2 certification is to attend the CSWIP 3.1 course and exam and once you have it already, you can immediately apply for the CSWIP 3.2 course and exam.
Hope this will help you in deciding which route is more suitable for you. Good luck!