Alas BUS2010 "Request for quotation" is poor in BAPI (mostly/only transactions?), and RFQ are hidden in the middle of package ME, not much help for research.
BAdI if you find one, more chance with an enhancement spot, but did you also look into IDoc and Workflow task, or even a standard report (not much hope I concede)
Another solution as table EREV is linked in SCDO with object REVISION, perform some where-used of FL REVISION_WRITE_DOCUMENT (which seems to write change document for version ?) until you find a suitable calling FM/Class/Report.
Regards,
Raymond