Kaveh
I think John is correct.
However,
You may be able to purchase an SWPS (Standard Welding Procedure Specification) This is a WPS already made and tested and has acceptance through much (but not all) of industry.
Walt Sperko (a man to be respected) helps us understand how SWPS apply to ASME jobs here
http://files.asme.org/asmeorg/Codes/CertifAccred/Accreditation/1036.pdfHere is an example of an SWPS for sale that covers carbon to stainless steel. "AWS B2.1-1/8-006 Standard Welding Procedure Specification (SWPS) for Gas Metal Arc Welding of Carbon Steel to Austenitic Stainless Steel (M-1 to M-8, P-8 or S-8), 18 Through 10 Gauge, in the As-Welded Condition, with or without Backing "
http://engineers.ihs.com/document/abstract/MHVEABAAAAAAAAAAI'm not suggestign this specific SWPS would be a good fit for you... Just an example
SWPS when applicable.... are less expensive than qualifying a procedure.