Hi,
I have gone through with article provided by Infragistics
http://devcenter.infragistics.com/Support/KnowledgeBaseArticle.aspx?ArticleID=010016
It is helpful but not able to complete the functionality using this. Please look into this and let me know some code snippet which help me to achieve this excel like key Navigation for UP, Down, Left and right keys for Hierachical Grid.
Sunil