You can not do what you want to do.
The games you want change the title screen don't use "custom title screen". They use the standard title screen which is coded in the Colecovision ROM BIOS itself , not in the cartridge.
In the cartridge rom you will find only the Text. "VENTURE" , "PEPPER II" etc... so the only thing you can change easly is if you want rename PEPPER II to PEPPER I for instance. But not put graphic title.
To do that, it is lot more complex, you have to dissamble the cartridge rom and Invert 2 bytes in the header in order the coleco do not display the default title screen and implement code that load your own pattern , Name and Color Table that you have also to include in your data section. that's a developper work , not a simple cut and paste byte at the right place.