If you want to avoid manual texteditor copy/past orgies, dir2dat may help you to create the datfiles.
dir2dat (in the Profiler), is a pretty simple datfile creator which scans a folder, reads the files and creates a datfile from it.
There is nothing like "load textfile xyz and use this as manufacturer".
There is however an option to use set description, year and manufacturer information from the currently loaded database. So if you got that option enabled and loaded a MAME profile in clrmamepro and now use dir2dat to create a datfile for a different (non mame rompath) folder, clrmamepro tries to match the created setnames with the MAME ones and then takes the information from that loaded datfile. Like "puckman" folder was found during dir2dat datfile creation, "puckman" is in MAME, it will automatically set the manufacturer/description/year tags from MAME in the new dat.
As I said...dir2dat is just a basic datfile creator....maybe DatWorkShopPro
http://www.emulab.it/utility.php can help you.