Not as far as I'm aware. The reason that they were able to do that with Halo was because it was LAN-compatible. It's a trick called "tunnelling". What you do is you hook your XBox up to a comp and trick the console's modem into thinking it's in LAN mode with another console. You then use your comp to hook up with others over the net. It's basically treated like a "long-distance LAN" connection.

SC2 is not LAN-capable, as far as I'm aware, simply because there's no need for it. You can't play with more than two players at once, and it plays full-screen two-player, so what would the purpose of a LAN be? Unless the XBox or PS2 versions are already online-capable (I wouldn't know, I only own the GCN version), then no, you're stuck playing it face-to-face.