Depends what club you are. If you're a rich big club with high rep, send your scouts to the academies of other high rep clubs such as Barcelona or Arsenal. Any kid with the 'regen face' is a regen (duh?). Get scouts to report on them. When te scout watches a player in a match, he'll report on other good prospects in the game - possibly from both sides.
for some reason, year after year, my scouts tend to unearth gems in Watford's youth set-up.
What I do is get as many scouts as possible and send some around the world and some to regions (South America etc) and youth competitions. Also when you assign them add a filter of person age at most 22 or even younger if you want.
Set the age to 17 or under and then set value as minimum of say £2m. This is not foolproof but it gives you an idea of the re-gens who are valued highly for their age and gives you a good start on the possible stars.
I have done this and found many good players this way - also found some duff ones as well so make sure you scout the ones that look good.
On or around the dates in each of the countries featured in that threads list, you can either use the standard search (if your clubs scouting knowledge covers the different countries well enough), or manually search through u19's/u21's of the countries national sides, club sides.
It can be quite painstaking searching manually of course, but certainly worthwhile if you uncover a hidden gem. Don't forget you can also send your scouts out to a particular country if you know when the regen dates are, along with getting detailed scout reports when you find players you're interested in.
i search nations under 19 sides regularly. not guaranteed to always find the best but i've had a fair bit of success this way. get your scouts out as well. brazil, argentina, france, italy, spain all tend to have good regens