Just upgraded to v6.0.0.2475 with Japanese input on my Torch 9800. It works perfectly. You can find the last release :
9800jAllLang_PBr6.0.0_rel2475_PL6.6.0.207_A6.0.0.5 46_Taiwan_Mobile.exe
BlackBerry Handheld Software v6.0.0.2475 (All Languages)
Package Version: 6.0.0.2475
Consisting of:
Applications: 6.0.0.546
Software Platform: 6.6.0.207
File name: 9800jAllLang_PBr6.0.0_rel2475_PL6.6.0.207_A6.0.0.5 46_Taiwan_Mobile.exe
File size: 194.88MB