Personally I would take the high road 
Celestial gnome paly 3/wizard(illusionist) 3 (or sorc) and then level X in a custom made prestige class that you and your dm work out that makes you a paladin/wizard(illusionist) or sorc and gets you closer to where you want the character to go.
Possibly even Celestial gnome paly2/illusionist 3/Divine Fallacy X (gotta love it..lol.. paladins are called lawful stupid after all.. but not to their face)
It seems like the best option to me to keep your character as close as possible while making it more like how you wanted it anyway. It will work!

Celestial gnome paly 3/wizard(illusionist) 3 (or sorc) and then level X in a custom made prestige class that you and your dm work out that makes you a paladin/wizard(illusionist) or sorc and gets you closer to where you want the character to go.
Possibly even Celestial gnome paly2/illusionist 3/Divine Fallacy X (gotta love it..lol.. paladins are called lawful stupid after all.. but not to their face)
It seems like the best option to me to keep your character as close as possible while making it more like how you wanted it anyway. It will work!