Simplest what I found was using netstat -e shell command and processing its output.
It will not give you information on specific proccess however, just on general traffic.
Function below works for English WIN 8.1
Function NetStat_win8
Dim strLine
Dim varMBIn, varMBOut
strLine = getCommandOutput("netstat -e")
strLine = Left(strLine,InStr(strLine,"Unicast") - 1)
strLine = Ltrim(Right(strLine,Len(strLine) - InStrRev(strLine,"Bytes") - 4))
varKbIn = Left(strLine,InStr(strLine," "))/1024
varKbOut = Ltrim(Right(strLine,Len(strLine) - InStr(strLine," ")))/1024
log.Message varkbIn &"/" & varkbOut
NetStat_win8 = Array(varkbIn,varkbOut)
End Function
