Installation instructions:

1. On your device, go to Settings-->Design
2. Click on "Theme" button.
3. Click on "Download themes previews" (a preview list will be downloaded to your phone, you must have a connection)
4. After download, you will be able to navigate through themes previews. Click "Install theme" to download the theme you chose.
5. Save settings and done.

Forum thread
By Dens

OMNIA SPECIFIC

PocketShield can convert HTC themes to Omnia resolution. Image quality will be fair enough, but not the best you could get. For high quality themes for Omnia you will have to get an Omnia specific theme. Even the ported HTC themes can have high quality for the Omnia, it depends on how 'carefully' images are resized.