Of course you can do OTA updates manually, without ROM Manager Premium.
- On the handset open up a browser of your choice and navigate to http://download.cyanogenmod.com/
- On the left column, under the "By Device" section tap on the codename for your device (e.g. "passion" for Nexus One)
- Optionally, you can filter the download list by type (Stable Vs. Nightly) by tapping on the type right above the list of downloads.
- Tap on the filename to begin download. Obviously a WiFi connection is recommended because the ROMs are fairly large, at around 100 MB.
- Once the download completes, reboot into Recovery (Clockworkmod, Amon-RA, etc.)
- Perform a NANDroid backup, so that you can do a restore in case something goes wrong in subsequent steps.
- Wipe Cache and Dalvik-cache partitions (you'll need to find the relevant menu entries in whatever recovery image you are using.) This step is not mandatory, but can help resolve stability issues, so always I perform it.
[Edit] 7.a. Note that if you are upgrading to the same ROM (i.e. flashing a newer nightly of CyanogenMod) you don't have to wipe data. This way all of your current apps and settings are retained. Only if you change to a different ROM altogether (i.e. going from CM to a Sense port) would you need to start over by wiping the /data partition.
- Select to flash a Zip from SD Card from the "download" folder (could be a different directory, depending on the browser you are using.) This can take a while, and the progress bar might appear to be stuck, but don't cut power to the phone or you'll risk corruption. Once the "success" message appears you can move forward.
- Optionally flash an alternate kernel image (for overclocks, etc.)
- Reboot your phone. This step will take longer than usual, since the caches are being rebuilt.
ROM Manager Premium automates most of these steps so that you don't have to muck around the recovery too much, but you can always to this yourself. It's still Over-The-Air, since you're not hooking your phone up to a PC to transfer the files.
Furthermore, you can even automate the notifications of new builds being posted for CyanogenMod via RSS feeds. The trick is that the CM download page doesn't provide its own RSS feed, so you have to create your own via one of the free services:
- Get your device's link (e.g.
http://download.cyanogenmod.com/?type=nightly&device=passion for Nexus One Nightly builds.)
- Go to one of the free RSS-from-website creation services and create an RSS feed for the link above. You might need to tinker with advanced settings to get the listing. For example, I created this RSS feed for Nexus One nightly builds.
- Subscribe to the newly generated feed in your favorite RSS reader (e.g. Google Reader
- Use an Android RSS reader app that has notifications feature (e.g. NewsRob) and set up a notification for this feed.