Yesterday I googled “Omnia 2 android” and was surprised to find Omnia2 supports android 2.2 Froyo, just from several days ago. If you have decent size SD card (larger than 2G), to install Froyo is straightforward, look here. The install will not affect your windows mobile.
However, I have only a old free 1G SD card from GPS software. So, I made minor changes to the installer. To use it (suppose you unzip froyo_beta1_1024.zip to /froyo):
1. cd ~
2. zcat /froyo/o2beta/sd.cpio.gz |cpio -idmv
3. replace init with the attached version
5. cp sd.cpio.gz /froyo/o2beta/
6. connect phone at Linux, (at phone setting, set usb connection using mass storage->storage card, instead of activesync)
7. use fdisk and mkfs.ext4 to make an ext4 partition covering whole sd card
then, you could install froyo with usual way.
After boot to Froyo, it complains there is no SD card. To bypass this, I go back to windows mobile and mount the sd card with Linux, and modify init.rc at its root, to mount internal storage to /mnt/sdcard.
BTW: I do not know how long time the sd card can last, as during the install, I always meet file system errors, and sometimes, met erros like: “request_suspend_state: wakeup” during reboot. I tried several times util successfully install Froyo.