Hi,
You can create a virtual page and then link to your physical.aspx page using the fully qualified url in the page settings, ie instead of ~/somepage.aspx you put the full url like http://yoursite/yourcustompage.aspx
However that is not a very elegant integration, the best thing is if you re-factor your .aspx page into a UserControl (ie .ascx), then you can plug it in on any virtual page just like any other feature. See the hello world developer examples for more info.
Hope it helps,
Joe