Why do you want to do this?
I had a look at the source code and the Passport class has a public keyPath property that is used to determine where to store the keys. However I dont see how you would go setting the path
There is a way to load thd keys from another location so might need to manually move the keys
Passport::loadKeysFrom('/var/http/path/to/files');
These tests might help
To be honest I would leave as is unless you have a deal breaker reason to change