Karsten,
This shouldn't be too difficult
1. On the source machine, open the edit keyword dialogue, there you will get the option to
export keywords to a file.
2. Do that.
3. Copy file to destination machine.
4. On the destination machine, open the edit keyword dialogue, there you will get the option to
import keywords from a file.
5. Do that.
Done
Note: to open the keyword dialogue, open either the IPTC info or IPTC stationary pad, click on the arrow next to the keywords field, this will show the complete list of keywords, as well some options at the top. choose "Edit Keywords". This is the edit keywords dialogue.
Hope this helps