First of all, install CBE, and setup your build env, you could refer to Matt Keenan's Blog. You also need to install the following depended packages,

$ pfexec pkg install SUNWPython26 SUNWgnome-python26-libs SUNWdbus-python26 SUNWpython26-xdg

Checkout the inputmethod repo, and link /usr/bin/python2.6 to /usr/bin/python,

$ inputmethod/spec/build-im.sh ibus*.spec

Then, export GTK_IM_MODULE=ibus and XMODIFIERS=@im=ibus in $HOME/.profile, re-login. After that, you would see an [i] icon in the tray-area, click the "preferences" from the popup menu (right-button click), and add the input methods you want to use in "Input Methods" tab.

Please NOTE, there are still some unfinished tasks, like the 64bits gtk_imm, SUNW_PKG/SUNW_LOC etc,  that I will address by the end of this week. And since ibus-chewing requires a higher version of libchewing, which breaks the API/ABI compatibilities of iiimf-zhTW-twle-chewing, I did not include ibus-chewing so far.