you dont need the intermidiate updates
install 12.1.0, and then:
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This update includes all the improvements that were released in all previous Office 2008 for Mac updates. For more information about the improvements in a previous update, click the following article numbers to view the articles in the Microsoft Knowledge Base:
953822 Description of the Microsoft Office 2008 for Mac 12.1.1 Update
956344 Description of the Microsoft Office 2008 for Mac 12.1.2 Update
958267 Description of the Microsoft Office 2008 for Mac 12.1.3 Update
unquote