Is it possible to use row access locking when using SCRIPT command in Teradata

Question

I'm trying to process the data in the table using an external script (Linux binary) with the SCRIPT_COMMAND function. However I cannot make it work so that row access lock is applied. By default read lock seems to be applied for the whole table.

This is an example - the script command is not important.

EXPLAIN SELECT * FROM SCRIPT
( ON (SELECT * from user1.test_table)   
SCRIPT_COMMAND('echo test') RETURNS('text VARCHAR(30)'));

This returns

 Explanation                                                              
 ------------------------------------------------------------------------ 
   1) First, we lock user1.test_table in TD_MAP1 for read on a     
      reserved RowHash to prevent global deadlock.                       
   2) Next, we lock user1.test_table in TD_MAP1 for read.          
(...)

I tried the following query:

EXPLAIN SELECT * FROM SCRIPT
( ON (LOCK ROW FOR ACCESS SELECT * from user1.test_table)   
SCRIPT_COMMAND('echo test') RETURNS('text VARCHAR(30)'));

But it is invalid.