Okie... first If u r working on a midi track u r in fact working on information/ data not in audio per se... when u use the midi out of that track 2 a machine or a virtual instrument then u get a few sounds (or not depending on the data u r sending, settings, etc...) ... so U ain't gonna get filters on data...
if u r using that midi track 2 "play" a virtual isntrument or something then u can just open it's pannel (in fact works 4 basically any plug in or VST i) then press the little W button, press play .. play with the knobs you need... stop, U have just created an automation track in the main arrange page... now press W again (2 deactivate) then R (read)... now when u press play u should have yer automated filter sweep...

If u r using an external synth U have 2 record yer knob tweeks 2 ..

If u know the Midi Controller number of yer filters just go to the main page... click on the drop down list u find in the key editor (piano roll) were u generaly find velocity... if u can't find that controller just press setup.. now from the left list choose the controler and add it 2 the right list, ok... now drop down the list again and there u should find the controller number u added... just use the pensil 2 draw it...

If u've just recorded yer knob tweeks when u go 2 the key editor and u press the drop down list (where u generally find Velocity) u'll find with an * the controllers u've just recorded...

phewww.. after a few times u'll understand this isn't as complicated as it look's!!!

Z