You should give Tritical's EDIUpsizer a go. It's built off of NEDI. He also has a FastEDIUpsizer, but I don't know if you are sacrificing speed for quality: http://bengal.missouri.edu/~kes25c/
Moth3r's linked script seems newer, but may be very similar. NNEDI (instead of standard filter flavors) is needed when upscaling by large factors.