There are all kinds of ways and tools to help XOGing.
After the Integration guide there is a XOG board and there is a tutorial XOG - The Basics...
The discussion on tools and migration options takes a new round every now and then.
Some of it is under
Data Migration Opinions?
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Keri Taylor has written guides for Style Vision and Mapforce
XLS --> XML Conversion using StylusStudio2010 and Altova MapForce201
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Mike Kolasa was developing a GUI for the management of the files during XOGing.
There are commercially available adapters for integrating Clarity with other systems including Excel.
eg from DigitalCelerity
http://www.digitalcelerity.com/Resources/Documents/Clarity%20Connect%20v2%200%20-%20Clarity%20Integration%20Adaptors%20from%20Digital%20Celerity%20LLC.pdf
ITRoissolutions has PPM Excel Interface
http://itroisolutions.com/ppm_excel_interface.html
It is up to you how much effort you want to put into the tool and how much effort does you data amount and transfer frequency justify.
Martti K.
P.S Then testing testing and testing so that you get your set up right and isolate things that don't go.