Well... It's not a trainer (and I don't have the ability to write one.) but I do have a cheat engine table(that really should be more organised...) that I wrote up a while ago that settles whatever you need to get past a normal game and probably a fair bit more:-
Number of turns taken on current mission (I believe I found the value for total number of turns but it shouldn't really matter anyway since the ones that are limited by total number of turns tend to be pretty high, this was used by me for S ranking certain particularly painful missions)
Love points for each route.
Attacks(and number of uses LEFT, it can't change max number of uses so going into a town and healing lower/raises it to the max again.)
Classes(note that you still need to level up once to actually gain the stats of the class you want, I also haven't tried if eternal/etranger skills work.)http://www.mediafire.com/?698kqi60t9s383y