Ok, so many people (incl. me) have some problems with signing their own ipk packages. I tried openSSL for windows, but failed.
Another way how to get an unofficial app installed on your devices is to enable dev mode and just install it via USB.
Here's how:
1.) have your ipk ready
(CMD --> palm-package yourappfolder | or download/get it from someone)
2.) kill the Palm SDK emulator and WAIT like 3-5 mins
3.) enable DEV MODE (just type:
upupdowndownleftrightleftrightbastar and click the icon - you will have to restart Pre)
4.) connect Pre via USB (just charge) - make sure no error happened; otherwise unplug and try again
Wait again 2-3 mins.
5.) CMD --> palm-install -d usb nameo****rapp.ipk
You need to be in X:\program Files\Palm\SDK\bin to do that.
Example (for my app):
palm-install -d usb com.mypreapps.lottopicker_1.0_all.ipk
6.) profit
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BTW: Do NOT waste 18 bucks on that stupid "Palm webOS, 1st Edition" book. It SUCKS!!! You can learn more from web and samples in SDK folder.
HAVE PHUN!