so here's my little mini walkthrough:

Start with a pure sdk system dump and deodex it - or use one of the dumps floating around here that are pre deodexed

you need to basically merge it with your latest ics build - I used my last compile of cm9 as a base but needless to say the closer the base is to aosp the better. You'll want to keep as much of the sdk pristine as possible basically just add in the things you need that are device specific such as:

any platform named hw libs from /system/lib/hw
your egl files from /system/lib/egl
your modules from system/lib/modules
wifi, bluetooth, and gps related files from /system/etc

you also will need your idc and keymap files and all the other device specific items out of /system/usr folders so your input methods will work - no idc files means no touch screen

the above error looks like a framework and lib are not getting along. Make sure the frameworks and all of the root /libs are sdk originals you can copy libs over to your sdk port that are not included however just don't overwrite any

make sure you properly modifiy the build.prop to match your device

copy busybox to the working folder into /system/bin and /system/xbin make sure every binary is executable! symlink /system/bin/busybox to /system/bin/sh and replace the sdk version of toolbox bin with the ics version

in ramdisk retain your device.init.rc but replace everything else with what comes in the sdk ramdisk - download the sdk properly and extract the ramdisk as cpio.gz extract it and use it as a base only adding the device specific .rcs that you need. If init.rc needs a few changes make them but as a rule you can usually just use your device.init.rc and keep the master clean. Be sure that init.traces.rc is in your ramdisk it's a new file for jellybean and it gives a crapload of errors when it's not there.

try not to load any wifi modules for initial tests - theres some changes that are screwing mine up if I set my modules to load on boot- it prevents a full boot haha

can't think of anything else off the top of my head
Why lie? I need a beer