See this link on configuring catalogs in ECC:
http://scn.sap.com/people/gabor.harsfalvi/blog/2010/09/22/oci-catalog-for-purchasing-in-ecc-mm-60
Also it is possible to use catalog in IW31 since R/3 4.7 .
See note 1092900 - PM/PS catalog connection
Regards,
Sushil.
