First you have to make the crystal report in design time possible to write or view Khmer Unicode
1.1. Copy usp10.dll (version1.465.4001.0) to C:\Program Files\Business Objects\Common\2.8\bin
1.2. Change fonts setting in Crystal Report, at VS2008, create a crystal report and go to Crystal Reports --> Design --> Default Setting --> Go to Fonts Tab, change all element to Kh System
II. View Crystal Report with VS Crystal Report Viewer,
Khmer Unicode is not rendering well.
(Under research)