You cannot apply an effect before Twixtor in Premiere unless it’s within a nested sequence, however you should be able to apply one after unless like Twixtor it’s accesses multiple frames per frame.
To apply an effect before Twixtor:
create a nested sequence, drop your footage in it, drop your effect there and then in the main sequence, set the color source to that nested sequence (eg video track 2 or whatever it is)
Are you using PPRO 1.5 or 2? As well does your material have fields?
If it’s the same Shadow/Highlight as AE (just got new PPRO 2 this week and have not installed yet), then it has a temporal smoothing option (thus accesses multiple frames somehow), therefore would probably require an additional level of nesting to work in Premiere correctly.
Pierre
RE:Vision Effects
Pierre