This's as simple as copying everything from the various archives in the same place (overwriting or skipping as needed, it really doesn't matter).
When you then run Office 2007 or Office 2010's
setup.exe, it will automatically discover available products and prompt you with a menu to choose what to install.
Bonus: if you put in the setup files for various languages, the Office setup will even let you choose which one(s) you want to install!
For Office 2007, you simply need to put everything in the same place.
For Office 2010, as there are x86 and x64 editions, you should not mix them; but if you start from a full DVD, which includes both releases, you will find an "x86" and an "x64" folder: inside each of them there is the full product setup with its own
setup.exe, and they are wrapped by an external
setup.exe placed in the DVD root which selects the right one for the current system.
You should use exactly the same approach, putting the setup files for x86 products in the "x86" folder and the files for x64 products in the "x64" one.
(Ok, I just discovered this and wanted to share it with SF :-))