I can mjlink an entire folder directory path usually for cache file etc, (ie to ramdisk because 1. faster, 2. upon reboot stuff gets cleaned up).

but how can this be done to a specific file? since can't find the settings in windows to ask it to write to different directory path.

take fontcache as an example, I wish to relocate this file into ramdisk but not the entire folder its located in, as those include some other stuff from other programs that do need file saving.