For anyone who is interested I've got it working: as an Address I tried to use dummy bit say 0x00 or NULL in ASCII and then backspace, but it didn't work properly, because NULL was showing some artifacts on a display. So I used 0x02 instead:
I2COUT 0, $5C, $2 [$08, "Hello World"]

Note:I2COUT/I2CIN ...

I am trying to use I2C communication with BS2p. The structure of the Basic Stamp command to send data on to I2C node is:
I2COUT Pin, SlaveID, Address, [data]
where:
Pin - is i/o pin 1 or 8
SlaveId - is ID of the I2C chip (our display - in case of LK204-25 should be 0x5C according to manual)
Address ...