To create a VCL patch all that is required is that you copy the source file (*.pas file) from the Borland RTL or VCL source folder to your application's project folder. You can then freely modify the file and it will automatically be compiled into your application.
NOTE: This technique should only be used as an interim measure. When Borland releases fixes for the VCL that address the original issue it is recommended that you remove the patch file. Make sure you remove the respective *.dcu files as well.
WARNING: When you modify RTL/VCL files in interface section, and you are using third party components without sources you won't be able to rebuild your project!