Firefox 32/64bit - no SCIM on 32-bit ff under x86_64

[Naoki <naoki valuecommerce com>]

I am running x86_64 rawhide with both 32/64bit firefox installed and have noticed that SCIM (Japanese input) only works in the 64-bit version.
Trying to work out why but ldd/strace have not revealed anything to me..  I'm assuming it's because I need a 32-bit version of scim perhaps but want to validate the theory before installing.

Can anybody quickly explain this one and/or offer a workaround?  oh, the 32-bit version is for flash naturally.