It's today situation... tomorrow you may have more...
In some other case we use small badi launched at the beginning of the script that just set memory variable to enable writing controlled by write back badi:
method IF_UJ_CUSTOM_LOGIC~EXECUTE.
" Allow write to ACT
DATA l_importact TYPE C.
l_importact = 'X'.
EXPORT importact = l_importact TO MEMORY ID 'Z_VALIDATOR_IMPORTACT'.
cl_ujk_logger=>empty_line( ).
cl_ujk_logger=>log( '=========================================================' ).
cl_ujk_logger=>log( '# Access to ACT is allowed now! #' ).
cl_ujk_logger=>log( '=========================================================' ).
endmethod.
The variable will be set for the current user for current session (current script file)
Vadim