Can winpkfilter be used to send packet as if it is coming from remote PC ( internet remote host like yahoo ? )
Sure. The easiest way for you to start is take and parse the normally received packet (intercepted from the network). You can do it with one of the network sniffers (like Network Monitor or Ethereal). Then just build your own packet with WinpkFilter on the same way. Of course it requires some understanding of how TCP/IP works..