This is how to set up a power saver profile in the style of the native HTC power saver. I am running a new rom and really missed the power saver function!
It will dim brightness to 0, turn off wifi, turn off auto-sync, and disable haptic feedback. You can obviously add others as you see fit such as toggle 2G/3G, set CPU speed, etc. I've just added the options that were previously part of the HTC function
1. New profile - "Power Saver"
2. State —> Power —> Battery level - Set at whatever percentage you like, I chose 'from' 0 'to' 25 (so when the battery dips below 25% this profile will activate)
3. New task - "power saving"
4. Add, from 'Net' - wifi - off
5. Add, from 'Net' - auto sync - off
6. Add, from 'Audio' - haptic feedback - off
7. Add, from 'Display' - Brightness - 0
8. Add, from 'Alert' - Popup - enter text, for example "Power Saver Activated"
and you're done! I haven't figured out a way to disable the profile if the phone is on the charger, which is another aspect of the native HTC feature, but it's not all that essential I guess.
You will have to add an Exit Task so the features come back on when the battery is back over 25%. Do this by clicking the 'power saving' task, selecting 'add exit task' then go through and add the opposite of everything added above!