What are the Fields in P6 R15.2 that are updatable from Excel?

I have a Project Schedule that our Client and us sharing the same Project Schedule and I want to load Budgeted Labor Hours but do not want my client to see the labor hours.

So I need to go around and the only solution for me is to use Excel as the median between my schedule and hours, the only problem is that I cannot update my P6 R15.2 with all the column with "*".

Please let me know how to import/update my project schedule from excel that has the "*" column on Excel.

Thanks.