Injecting data into a custom field


I have created a custom field and would like to run a query where I place a random string into each user's custom field. I can handle building the injection loop but from the looks of things, it seems all custom fields are BLOBed together so its throwing me as to how I would do this. Any help would be greatly appreciated.


in memoriam 1991-2020
The easiest (and most likely the most logical method) would be to use the appropriate data writers to set the information.