CS4: Add codec support

Question

Does anyone know how I can add support for a codec in Premiere Pro CS4 [Windows]?
I would like to have the XVID [not DIVX!] codec and the X264 [not H264!] codecs to be supported by Premiere Pro, because I cant seem to import any of my custom converted videos [well, actually importing works, but Premier only shows 1 frame, and sometimes a bit of sound...]
It seems like Premiere Pro doesnt support anything! [except for the WMV codec, but that s*cks...]
Please tell me how to add codec support to Premier Pro CS4!

Answer 1

Well, let me explain it all now:
-I used a video camera to shoot some clips.
-Those clips were automatically encoded with the H.264 codec. [as it is Full HD footage]
-When i tried to play these files on my computer, it displayed weird black bars on the left and right.
-So i wanted to convert those files using another codec, to make them look properly on my computer.
-So i opened the videofile with Any Video Converter Pro to have a look if that program does read the format properly.
-It seemed that Any Video Converter Pro was able to read the file properly.
*I think that is because it has build-in codecs or something? ... on the other hand, the codec i use a lot, x264 and xvid, which are available in the program, arent available by default: i installed them. So the problem would be on my computer [Vista 64bit] and laptop [Vista 32bit] not being able to handle the H.264 codec properly, as Any Video Converter Pro was able to read them properly.
-Using the fact that A.V.C.P. [Any Video Converter Pro] was able to read the file properly, i converted it to another HD codec: X264, which my computer can display without any problems at all: now the black bars on the side are gone.
-But now I want to use Pr to start the videoediting of multiple clips. Unfortunatly, Pr isnt able of reading the X264 codec.
-So i tried other codecs, like the ones which are supposed to be supported: MP4 , MPEGII, Microsoft AVI 1, Panasonic DV, XVid, DivX and WMV.
The only format which Pr seems to like is WMV:
-With the other codecs, it only shows the first frame, though it does import the files [no errors given].
-Only the Panasonic DV and MPEGII codec gave the error of not being able to be imported.
On to the information of the sequence and the used footage:
SEQUENCE:
Capture Format: HDV
Preset Used: AVC-I 100 1080p30
FOOTAGE:
Container: AVI
Codec: X264 [originally H264, explanation above]
Audio: MP3
Resolution: 1920x1080, aka Full HD
Video Bitrate: 6000
Just for the record, here is the comparison of two identical files, both the same footage, left is converted to X264, right is the original, using H264.
Here is the comparison of the two files when played; again: Left X264, Right H264: [both reduced in size, to make them fit in this image I also removed the persons, for privacy reasons.] I tried different media players, but all show the same: GOM Player, Windows Media Player, VLC Media Player, Quicktime Player, RealPlayer. Also installing the Full K-Lite Codec Pack didnt make a difference.