introduce diversity. Alter the skin-pigments of the main characters. Change their names. 'Shinji' becomes 'Tyrone', for example. Give them racially diverse voices too.
Westernize it. 'Tokyo' becomes 'Pittsburg'. Mirror scenes of cars driving so the driver's side is now on the left, not on the right. Also edit any text that's in kanji or hiragana etc. to be american english. Ramen becomes spaghetti. Onigri becomes a twinkie. The kotatsu becomes a tablecloth.
Chop out anything that might be perceived as making the product unmarketable. Do it like how 'Gatchaman' became "Battle of the Planets". Fill in the cut-out parts by adding a minor character like 7-zark-7 who narrates for the kiddies, with stock animated sequences that are repeated from episode to episode cheaply and easily, just change the dialogue.
Edit the dialogue to remove anything that might infringe upon western PC-notions of gender roles. Example: the female lead offers her sempai a bento lunch, telling him she cooked it for him in her kitchen. So, change it so the girl says she bought him lunch, with the money she earned from her part time job tutoring other students in mathematics.
Edit the dialogue to remove all japanese notions that war is evil and stupid. Make the characters glad to fight, rather than viewing it as a morally bankrupt exercise in destruction and futility.
Edit the dialogue of the classroom sequences (there will be a high school, naturally) so instead of the characters being keen students, they will be lazy and slothful so the audience can relate to them easier. Also change 'english' lessons to 'spanish'.
Wow, maybe I'll get a job at Funimation or something...