Shugenja/Wu-Jen Double 9s

[Kennisiou]

Is it possible to achieve Double 9 casting in these classes by level 20? I feel like it's not, but if anyone knows any shenanigans that can help I'd like to know.

[Forrestfire]

Wu Jen 1/Shugenja 2/Mystic Theurge 10/some other dual-casting PrC 7

Use Versatile Spellcaster and Precocious Apprentice to qualify for MT early, then go to town.

Your choices for the second prestige class depend on the amount of work you're willing to put into qualifying. The easiest way that I can see to do it is to dip one level of Wildrunner to get trackless step, then take six levels of Arcane Hierophant. Requires half-elf or elf, but you can go:

Wu Jen 1/Shugenja 2/Mystic Theurge 10/Wildrunner 1/Arcane Heirophant 6 and get get 17th-level spellcasting out of Wu Jen and 18th for Shugenja.

[Chronos]

The easiest 4th-level entry into Mystic Theurge would be from an Illumian-- Everyone else needs too many feats. After Wu Jen 1/Shugenga 2/MT 10, you can afford to lose two more levels on each side. I think Legacy Champion would do it, if you use it to advance Mystic Theurge.