Hello Wilman,
I would recommend using the following parameters/values in your custom service:
~TRANSACTION zTEST
~WEBGUI 1
Then test it.
There are parameters that do not exist or are no longer valid.
About the custom theme, please read the following SAP notes:
2080444 - How to find the version of the SAP GUI for HTML style sheet
1787656 - SAP GUI for HTML in portal: Style sheet is not loaded correctly
I hope this helps,
Cris