Ups...
Not elegant 
May be something like:
*SELECT(%F%,GROUP,VERSION,ID=$TGTVER$ AND GROUP=FORECAST)
*SELECT(%B%,GROUP,VERSION,ID=$TGTVER$ AND GROUP<>FORECAST)
*FOR %FT%=%F% //FORECAST
*DESTINATION_APP=Finance
*ADD_DIM InternalOrder = IOGeneric
*RENAME_DIM AccountC=AccountSKF
*SKIP_DIM = ProjectID
*SKIP_DIM = LineItem
*SKIP_DIM = AssetClass
*WHEN AssetClass
*IS *
*REC(FACTOR=1,VERSION=$TGTVER$,COSTCENTRE=COSTCENTRE.FCGROUP,DATASRC=Input,AccountC=AssetClass.DEPN_EXP_ACC)
*ENDWHEN
*NEXT
Vadim