@Church Inquisitor:
There are Lawful good Kelemvor Clerics?
There are Kelemvor Paladins?
Then there is a LG part to the church of Kelemvor, which means you qualify for the PrC.
A reasonable DM won't think twice about it, tough mine needed a bit of time to digest my reasoning
I played a Cleric/CI of Hoar, who is also LN but does have LG Followers and "revenge, retribution, poetic justice" for his portfolio.
Wasn't there a Feat called "Heretic of the Faith", that would allow getting a domain, your god didn't offer normally?
Taking that for War domain would allow a Kelemvorite to enter Ordained Champion.
It loses out on Spellprogression, but makes up for it with 1 additional Domain, Channel Spell(like a Duskblade, but holds charge on a miss) and "Smite anything, not just evil".