I know you don't have the cash to get *the* pedal. But I found this thread:

http://www.epinions.com/review/Mxr_EVH117_Van_Halen_Flanger_Pedal/content_435495603844?sb=1

"The four knobs control Manual, Width, Speed, and Regeneration. The Manual knob the degree of the effect and the Width controls the intensity of the effect. Turn the Width off, you turn off the “delay”, turn it up and you get that “sweeping” sound. The Speed it the fun knob. It controls….get this…the speed of the effect (go figure). The speed of the sweeping sound is increased (or decreased) with this knob. Turn it up, and you get a ray-gun effect. From basic swirling sounds to space ship/ray gun sounding effects are achieved this way. The Regen (or Regeneration) knob allows you to reproduce the sound over itself. Kind of like Reverb or Echo effect on an amp (or other pedal)."

The character of the MXR Flanger's internal component parameter controls is really key to that sweep sound. Of course, D-Tuning the guitar to Open-D and using the bridge humbucker through a high-gain EL84 type amp would be other components to be mindful of.