A summary screen (like the company summary screen) is not easily changed. It is partially constructed from EntryGroupBlocks defined in meta data and other screen components that derive from hard coded elements within the dll.
The Company Summary screen calls the CompanyBoxLong, AddressBoxShort, and personBoxShort with the phone/email area assembled not from a 'screen' but the types of phone/emails described in the custom_caption table as translations.
You can permanently add or remove fields from the company summary screen by deleting them from the meta data definitions of the screens. Or you could use create scripts to remove fields using a clause like (Hidden = true;).
But you can not remove individual screen blocks from the summary screen because these are hard defined within the internal actions.
So this makes it impossible to change the structure of the summary page within server side script. But it is possible for you to make changes to the rendered structure of the script by using client side jscript to change the HTML.
For example it is perfectly possible to change the buttons on a screen and it is even possible to change items like the opportunity pipeline summary area. If you follow the tag links on the right of the screen you will find articles that explore how this can be done.
You have two main ways of delivering the code into the client that can make the changes that you want. These are firstly via the Custom Content box of each meta data defined screen and the second way is by using the Caption property.
I've written other articles previously that describe how to use dummy fields to deliver HTML into the browser.
A major dynamic rebuild of the HTML within the browser can be daunting to code and it may actually look odd to the user and hammer the perceived performance of the screen.
An alternative would be the complete substitution of the screen by an ASP page but that is another story.