The deployment and implementation included in Wictor's article is only suitable for 2010 due to how the solution package would be deployed and how the custom web part is referenced in the custom page. In 2010 sandboxed webparts are referenced using the SPUserCodeWebPart wrapper which does not exist in 2007. In 2007, you can reference the web part directly (don't forget to register the namespace and assembly though).
If you need to target 2007, 2010 (sandbox/user solution) and 2010 (farm solution) then I would suggest you develop 2 different solution packages: one for 2007 and one for 2010 (sandbox/user solution). To cover the farm solution requirement, you should be able to use the sandboxed solution - as far as I am aware, you can install a sandboxed solution in the same way you would a farm solution.