Been there - done that!
What version of Navision are you using? My answers here are based on version 4.00 and SQL Server database.
You must have a version that allow you to dissable the “Validate Code Page” option (under Alter Database). This allow you to have more than one codepage in the database. Just remember that they should not be entering Chinese characters in indexed Code fields in Navision as this will you unable to use Navision’s build-in backup function.
As for Citrix, then you need to separate Citrix servers, where the one for Chinese must be installed with Chinese support in non-codepage programs.
Well there is properly more to it. But try a search here, the question has been asked many times (ie. by me) and there are my good tips here. Otherwise ask again. We’ll love to hear “your story” too…