Hi Stanislaw
As far as I know VUSREXTID is the only option for mapping certificates when on NW701.
Later releases allow for mapping of certificates against other attributes i.e. alternative name. This is what we use with certs issued by SAPSSO 2.0.
Rule-Based Certificate Mapping (Transaction CERTRULE)
https://help.sap.com/saphelp_nw74/helpdata/en/c8/30fd902dc8473b9e59db1576cc784b/frameset.htm
login/certificate_mapping_rulebased = 1
Not the answer your are after, but hope it helps.
Rgrds
Craig