Yeah, it quite simple since MIUI v4 has separated framework with Android's framework so it get more portable now.
I used most part based on CM9 except framework, app and some lib, custom part from NS1 MIUI ICS v4. I have made some change in init.rc & init.mapphone_umts.rc to debug boot process (additional debug scripts and config are included in this post as attachment). Debug config & script will create a folder inside /data called boot (/data/boot) and will write some helpful information in that folder. NOTE: you must change mode for file in bin/ folder to 755 after replace it on your phone, else your phone will get boot loop & won't bootable included OR mode.
Remember that my MIUI ICS version was born from combined of CM9 and NS1 MIUI ICS v4 (there are only NS1 at time I made that port) so you can compare these versions to spot changes I made.
For Wifi & 3G problem I think it should get fixed by use settings and module / binary from CM9, try to use /system/bin/rild & /system/bin/rild_tcmd from CM9 (CM7 or stock may work also). I have too busy at this time to continue debug & development anything, I will post some modded versions (Stock 2.2.1 based with removed bloatwares & installed GO suite) to Google project page as reference and for guys who interesting on use it.
No money, no honey!
Desire Z T-MOUS G2
Developer's keyboard mod