Hello,
check the process in WDDOMODIFYVIEW method from IDR_VIEW view (Web Dynpro Component FPM_IDR_COMPONENT).
I guess you are not in SRM 7.0 release, but process should be the same: in SRM 7.0, SC labels come from /SAPSRM/CL_CH_WD_MAP_TB_SC class (text symbols).
Regards.
Laurent.