I can't belive it but finaly I did it!
I did everything the same and only one difference was that I didn't use plpcfgbt at all.
There is sometching wrong about plpcfgbt.exe (same for gui).
It showed me that my rom file is configured for text mode, no stars animation, bios font etc. I didn't change any option, just replace module in my BIOS and flash.
And now there is a Plop Boot Manager in Bios setup (instead of Network) and when it starts it's like a menu and there is a stars animation, zoom windows etc. Weird, isn't it?
The best thing is that I can finally boot from USB!
Elmar - thanks for your support!