From the link above I see that the camera support ONVIF. Therefore, I really recommend you to switch to Netcam Studio since it support ONVIF and when adding the camera just use the tab ONVIF source and you will be up and running quickly. The new web client is excellent! Here you can read more and download NCS.
However, if you insist on using webcamxp you must use the built in Universal source filter where you can add IP cameras. Do the following in webcamxp
-right click on new camera and select