If the correct files and tools are used it will work just fine.
Cam files in the map folder, activate with the keygen of your choice, and done.
You can even keep the .dct file for the cams for future maps as it won't change.
This way it might be easier
I hope you got a backup with the .dct file of the the speed cams?
And please define where and how you can/can't see the cams.
In the menu? In the settings? Or on the map?