New Post: How to install files in a folder based on custom property

I have a ManagedProject that installs some files in %ProgramFiles%\Company\AppName.
Then I have some files that has to go into a folder that is resolved by reading a registry value.
How can that be done?

I can read the registry value using the Load method, but I guess I have to set a custom property there that I use for "new Dir", but I cannot figure out on how to do it.
Any suggestions?

Best regards
Flemming