Nevermind, i figured it out. Here is how to do it:
1-> Click start, Run, In the window that opens, type "cmd" minus the quotes, and click OK.
2-> A DOS window will pop up. You will see a blinking cursor next to a prompt. If you have "C:\SomeFolderName\SomeFolderName>" Where SomeFolderName is the name of any folder in your drive, go to step 3. if you have "C:\>" Skip to step 4.
3-> Type "cd.." Minus the quotes and press enter. If there is still a folder name there, repeat this step again. If there is a "C:\>" Go on to step 4.
4-> If this is not the correct drive that contains UT2004, type "X:\" or "X:" Where X is the letter of your drive. If the correct drive letter is displayed, go on to step 5.
5-> If this is not the directory that contains your UT2004 folder, type "cd Basefoldername" Minus the quotes, where BaseFolderName is the appropriate base folder containing your UT2004 directory. If you still have not reached the correct directory, type "cd NextBaseFolderName" minus quotes, where NextBaseFolderName is exactly what it says. Repeat this step until you are at the correct folder that contains your Ut2004 folder.
6-> if at the correct base folder that contains UT2004, type "cd Ut2004" Minus quotes, then enter, then type "cd system" minus quotes then enter.
7-> type "ucc exportcache OnslaughtBP.u" minus quotes, and press enter. This will export the files needed to add the ECE bonus vehicles to the cache, where the CL 5.4 can access them.
8-> Close by typing "exit" minus the quotes, and you're done.