GET versus POST in OCI Catalog

Hi Experts -- how do I get SAP to send POST command instead of GET command when it sends user id and password info to the vendor's URL?  I have tried using POST in the HOOK_URL (HOOK_URL = SAPEVENT:POST) and RequestMethod = POST but, GET is still being received by the vendor. 

Additionally, even though my URL setting does not include user id and password, SAP still sends them as one string attached to the URL.. How do I insure the id and password for the site are sent separate from the URL?

Thanks

Doug.