so has anyone figured out how to install apps to the SD card yet ??
see this post
MIUI ROM 2.3.30 ROMS [ICS] & [GB]
Don't know about for the ICS roms, but for Gingerbread...............
Miui has built in A2SD+, which is essentially Dark Tremor's A2SD. To use it, make an ext partition on your sd card. I typically use 1 GB, but it supports 2GB and perhaps larger. A2SD+ seems to prefer ext3 partitions. It is really a crapshoot if A2SD+ will auto work, more often than not I have to use terminal to get it working. (see below).
You can make the partition from your computer using gparted or using Rom Manager. Make sure you back up your sd card contents to computer when you make the ext3 partition because it will reformat the card. You want 1GB ext3, and 0 swap, and the rest FAT.
Once you have the ext3 partition, next time you flash miui, log in to market - errr google play and download terminal emulator. Make sure you go into the superuser app and allow root access. Then open terminal emulator and at the $ prompt, type in "su". Miui may prompt you to allow it, let it have root access. You will now get a # prompt meaning you have root access. Then type "a2sd install". It will start changing permissions and moving apps. It will reboot. Once it reboots, you can also move the dalvik cache over which will free up even more space. To do that, open terminal emulator again and type "su" and then at # type "a2sd cachesd" . It will again scroll a lot of stuff and reboot.
What you have done with all this is symlink the phone's internal memory to the ext3 partition and miui will automagically move the apps to the ext3 partition on the sd card as you install apps.
Hope that helps.