I know there is the option /serverMoves but with that Winboard will save the moves in a file that pgn4web can't read.
Arena can do that and I think also ChessGUI, I think it would be useful if also Winboard could do that.
BTW HG thanks for all the work on Winboard, after years of Scotti's Winboard_X I've switched to the new 4.5 and I like most of the new features, though I still have to implement the new "protocol 3" commands.