Is it possible to override component model or view.html.php

[anagai]

When developing with Joomla for awhile you will most likely end up modifying the component files. This is not the most ideal process, since when you upgrade you will lose all your changes to the component files that comes with Joomla. Upgrading Joomla is just simply replacing all the files. From the one and only article on the subject on the entire internet at
http://community.joomla.org/blogs/commu ... -html.html and other comments elsewhere looks like you cannot do model overrides. The article is not describing a true override. Its a method to override within the component. When you upgrade you will lose that override code. All the overrides should happen in the templates that you create.

[JLW]

The only way to do a model override is to copy the entire core component, hack the copy, and then package the copy as a new component under a new name.

So you have com_content and also com_my_content. Menu items can use one or the other. The result is independent of upgrades.

But if security becomes a problem on the original component, it will remain a problem in your component (long after the core component is upgraded).

[mcsmom]

No that is not correct.
You can override anything.

http://community.joomla.org/blogs/commu ... -html.html

You need to place what you want in a system plugin.