After having some problems of creating preinstall application (PA) I found easy way to do it. I have tested on Symbian 3rd - N92.
Just create regular SA application. Run installation on the phone, choose install on memory card.
Take card out and set read-only permission on all files in /sys/bin/myapp.exe, \private\10003a3f\import\apps\myapp_reg.rsc, private\10202dce\[UID].is
Now you can put this card in any other phone it will behave as preinstall application with TYPE=PA.
What is good about it:
1) No need of another PA package troubles.
2) After you signed your SA .sis file you can use for both type of deployment: regular and preinstalled one.
You can not do any custom or condition steps during installation. For example if I want to have one card to be used for both UIQ and Symbian3rd phone it will not, since I will have to select what kind of files to install. In this case I'll need PA type, but if you need simple installation it's simple to use SA type of installer. I still can play with this. For example I use different UID for Symbain3rd and UIQ application and install them both on one card. Would be interesting to see what symbian will do when I insert this card in device.
What do you think?