After some struggle with EcmtAgent installation (initially application icon didn't want to appear in "Install. apps." folder) I managed to run it.
It seems to be working fine when bearer is Bluetooth (giving message "Listening"), but in USB mode it gives "Start Error -2" message.
Unfortunately, I need exactly USB mode, so Bluetooth will not work for me.
Searching in internet didn't give me something.
Device is Nokia 5230.
I develop native Symbian-C++ apps.
And I don't use Carbide, only Console Environment.
SDK is "S60_5th_Edition_SDK_v1.0".