You are working against the grain of the system by not building features the recommended way.
Instead of HumanResources.aspx why not make HumanResourcesModule.ascx as a feature that plugs into a cms page, this is how the entry point of a feature should be implemented, then if you need additional supporting pages for the feature you link from the .ascx to .aspx page and pass the pageid and module id
The problem with the way you are doing it is that since no page id is passed in no page specifc skin can be applied and without a pageid is the same as if passing in the home page page id, that is what makes it the default page.
You could solve it from your own code without follwoing this recommendation but you make more work for yourself.
You will have to so it in OnPreInit but after OnPreInit completes in mojoBasePage so that you change it after mojoBasePage
protected override void OnPreInit(EventArgs e)
// let mojoBasePage do its thing
// write your own code here to set it as you wish but you'll have to figure out how to do that from code in mojoBasePage
I think it is better work with the grain of the wood not against the grain of the wood by implementing it in the recommended way as an .ascx you will have less work to do, by going against the grain you have to do more work.
Hope that helps,