Need instructions on how to set TV code in a Hitachi remote model VT-rm392a

Does this help?

http://ir.premisesystems.com/search.aspx?m=HITACHI&l=VTRM392A

When you click the "copy" icon, data on the infrared code for each
function is automatically copied to your clipboard. You can then paste
it into Notepad or whatever text editor you are using.

The information you are seeking may be obtained from the owner's
manual.
Below is a link to the owner's manual Web page:

http://www.satisfusion.com/Hitachi/Manuals/Search.jsp

Please search on the model number of the unit rather than the model
number
of the remote.

If your model is not listed, hard copies of the owner's manuals are
available through Pacific Coast Parts at 1-800-379-7737.  Their hours
are 8
AM to 4:30 PM, Pacific time, Monday through Friday.  There will be a
$10.00
charge plus $2.50 shipping and handling.

Also, there is a hotline for technical or operational assistance. 
Call the support number at 1-800-HITACHI.  This office is open
from 8:00 AM - 8:30 PM Monday - Sunday. Please have your model number
ready
when contacting either number.

I hope this info will help you.