Update integration.md

Author: Behemyth

docs/plugins/conan/integration.md

@@ -24,6 +24,27 @@ You can customize this file for package metadata like name, version, and setting
 
 ## Migrating Existing Projects
 
-If you have an existing `conanfile.py`, follow these steps.
+If you have an existing `conanfile.py`, back it up and run `cppython install` to generate both files. Then update your conanfile to inherit from `CPPythonBase`.
 
-**TODO**
+```python
+from conan.tools.cmake import CMake, CMakeDeps, CMakeToolchain, cmake_layout
+from conanfile_base import CPPythonBase  # Import the base class
+
+
+class YourPackage(CPPythonBase):  # Inherit from CPPythonBase instead of ConanFile
+    name = "your-package"
+    version = "1.0.0"
+    settings = "os", "compiler", "build_type", "arch"
+    exports = "conanfile_base.py"  # Export the base file
+
+    def requirements(self):
+        super().requirements()  # Get CPPython managed dependencies
+        # Add your custom requirements here
+        # self.requires("custom-lib/1.0.0")
+
+    def build_requirements(self):
+        super().build_requirements()  # Get CPPython managed test dependencies
+        # Add your custom build requirements here
+
+    # ... rest of your configuration
+```