CAF Application Runtime Configurations for system portlets

Hi All

Even if i change the Integration server Credentials how the system portlets (wm_tn,wm_bam_instance,wm_rules) are working fine with out changing any environmet entries (user-name,password) and also calling webservice connectors without giving any exceptions like access denied…

please suggest is there any option to do the same for custom portlets

[b]wm_tn using webservice connectors for the below IS services