GB has ended development. You may wish to try separate kernels, but development for this phone has stopped.
As per there release topic,

Second 4.0 adapter, for what kind of models, we believe that stability and a smooth user experience is very important. So whether of MIUI existing 2.3 models, the 4.0 required to meet the basic conditions: the original (or the end of the stable package) 4.0 ROM, ≥ 512M, and the machine RAM, ROM, ≥ 1G; 2.3 models in the Nexus One, Desire, the G7, the Milestone and the HD2 four models will not support the upgrade to 4.0, this four models the MIUI support a number of models, to accompany us through the past 600 days and nights. We are very reluctant to you, will not forget you, thank you for your understanding.

Third, the other nine models (the HTC Desire HD, HTC Desire Z, the SAMSUNG i9000 is the SAMSUNG T959 is, the MOTO Defy / Defy +, the SAMSUNG I897 LG the P990, HTC the Incredible S-G11, the HTC Desire S G12, G, etc.), as long as the corresponding original plant (or the end of the stable package) 4.0 ROM, we will consider fit our testers has already begun on some of the models tested on a daily basis as their own personal host, when we confirm stable enough will notify the appropriate development plan; welcomes users of these models we recommend a stable bottom package, we will immediately test.

Fourth, currently on the market new models, we will consider the development to meet the basic conditions for the second point, and if the forum active users over 2000 models, also hope to remind us when to meet the requirements; MIUI unofficial among the developers of the model adaptation is also in full swing, as the supplement of the

This means that
  1. GB might recieve an update for major fixes. (Unlikely)
  2. The 9 devices listed might receive ICS IF
    1. The manufacturer releases 4.0
    2. They have more than 2000 active forum user
    3. They have more than 1GB internal space.
    4. They have more than 512MB of RAM
I am quite sure that the 2x will have Miui V4 as soon as ICS is available from LG. There are drivers missing right now that make CM9 a bit unstable and incomplete.

Have a look over at XDA-developers, developer Waijk improves MIUI for the 2x, calls it Wiui. it's good stuff, and he just released an amazing 2.4.20 version with great tweaks.

He also has a beta of Miui V4 already up and running, just too buggy for everyday use.

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