It took me enough thinkering with this process that I thought I'd share the exact steps.
Download:
[LoadPluginEx.dll] -- dunno exactly which package it came out of, but it's the one that works; I believe it requires v7 of the MS C runtime library (msvcr70.dll)
[oldPlugins.avsi] -- autoloading script
Make a subdirectory off your plugins directory and stick your preferred AVS 2.0x plugins there. Add LoadPluginEx2.dll to the same folder. (My DLLs are numbered because I was experimenting with several versions, but you can call it whatever you want so long as you update the script below).
Put the .avsi in your regular plugins directory. Open it in a text editor. Should look something like this:
LoadPlugin("c:\pf\avisynth2\plugins\old\LoadPluginEx2.dll")
LoadPlugin("c:\pf\avisynth2\plugins\old\DustV5.dll")
LoadPlugin("c:\pf\avisynth2\plugins\old\GuavaComb.dll")
LoadPlugin("c:\pf\avisynth2\plugins\old\PeachSmoother.dll")
LoadPlugin("c:\pf\avisynth2\plugins\old\SmoothHiQ.dll")
Change the path to your plugins directory if necessary, and add references to any other old plugins you may want to use now or in the future. Save.
You should now be able to integrate AVS 2.0x and AVS 2.5x plugins seamlessly without any calls to LoadPlugin. For example, here is a script I used on a recent video capture:
cap = AviSource("d:\sg-1.avi").ConvertToYUY2
#cap = AviSource("l:\sg-1.avi").ConvertToYUY2
#crop = cap.Crop(0,56,0,-64)
crop = cap # Lindsey's filters apparently don't like crops
comb = crop.GuavaComb(mode = "NTSC", recall=75, maxVariation=15, activation=40)
peach = comb.PeachSmoother(noiseReduction=30, stability=20, spatial=100, dot=FALSE)
peach = peach.Crop(0,56,0,-64)
decomb = peach.Telecide(order=1, guide=1, post=2, vthresh=45, show=FALSE)
decomb = decomb.Decimate(cycle=5, mode=0)
dust = decomb.PixieDust(limit=2)
resize = dust.LanczosResize(640, 360)
return resize
#return StackVertical(decomb, dust)
#return cap.AssumeTFF.SeparateFields
More discussion is [here] (Doom9). Enjoy! --richardberg