Running with an external STB as the active source on UK2.5.5
Code:
#iicget 0x42 0x02
Contents of address 02 is: b1
which appears to be mode 0x31.

swapping to the internal tuner changes it
Code:
# iicget 0x42 0x02
Contents of address 02 is: 8f
i.e. mode 0x0F

So I'd say that you are on the correct track as far as changing the mode of that IC goes (although you'll want mode 0x31).

I am happy to dump other register values for you if you need them, although it would appear that it will be a manual process of dumping each register one at a time with iicget! (iicdump wants a linked library that I don't have and just throws the error "BUG IN DYNAMIC LINKER ld.so: dynamic-link.h: 46: elf_get_dynamic_info: Assertion `! "bad dynamic tag"' failed!")