I have also tried render texture, i got rendering on object from new camera but cant find how to make that as mirror reflection in firstperson camera??
Reading is relay difficulty.
Create a shader called MirrorReflection.shader and copy past the code from the wiki into the shader.
Create a JavaScript file called MirrorReflectionScript.js and copy past the code from the wiki into the JavaScript file.
Did it myself along the tutorial on the wiki and it is working fine.
Edit: I attach a unitypackage file withe a prefab and the script and the shader thats needed , a simple ready to use mirror plane.