I'd just get a USB cable sorted out and connect with that first to sort out the ethernet addressing. You'll need to set up emplode to do this via the options button on the connect dialogue that pops up while emplode is trying to connect to a player.

If you pop up the "About" menu choice on the player, you will see what IP address and subnet mask the player expects to be on. If this is different to your network address range, unless you set up a static route pointing to the address your PC will have no way to reach it. Likewise, there will be no return route to the PC that the player knows of. You are better getting them onto the same subnet: USB and player config from emplode is the quickest way to do this.