Ok - I assume the reason why you want to change the namespace is so your clients do not know that it is Dotnetnuke that they are using - there is nothing wrong in this it is allowable under the licence - however if you take this approach then the package is no longer the standard DotNetNuke package and generally as to coding etc you are on your own as customized DNN packages are not generally discussed on the forum - [rules of the forum]

Next if you want to customise the framework then you will need to understand the code that builds it - so just changing the namespace or just changing the displayed name dotnetnuke during the installation to your own product name will require a fair amount of customisation and thus a fairly good understanding of the code you will also need to recompile it. This will also mean that you are restricted in updating the code when version changes come out because you will need to make the code changes in the new version.

There are hundreds of customised DotNetNuke packages out there but you should understand that as far as the customisation of the standard code goes you will not find answers to how to do the customisation on the forums.[ the core tram get a little upset when we talk about customization of the core rightly so as you mainly customize it to sell it as your own product or a value added product and of course the core team does not get any benefit out of it]

however to start you on your way start in global.asax.vb - this should lead you to install.aspx and onto update.aspx - I think in version 3 all of the code you will need is in these files. It may be different for V4 however.

If you want to change the actual name of the dotnetnuke.dll then that can be done - simply change the namespace in each code page and any reference to the namespace in the core and 'core' modules and if you have 3rd party modules then you will need the source of them so that you can do the same in each of their code pages. This is a major job and restricts you to 3rd party modules that come with source.

The other way over your problem is for you to install the DotnetNuke for your clients - they then do not then see the reference to DotNetNuke.  At some stage a client is going to realise that they are running DotNetNuke no matter how you try to hide it - bit like trying to hide Windows. So rather then just change the name do some value adding to it to validate the reason for the cost of your package over a client simnply downloading a stock standard version of DNN.

I package my customised version of DNN as FeralSoftNuke it is a highly customised version of DNN but I make no attempt to hide the fact that it is built on the DNN framework - the extra bits I provide to my clients and the support validates the extra cost they willingly pay. This is a better approach then simply changing the namespace.