I am not aware of a Standardize Attributes function in JSL. I assume that because it is so simple to loop through a list of column to apply the same attribute, that it doesn't make sense to have a stand alone function.
To get a list of selected column just use
Names Default To Here( 1 );
dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
dt << Go To( :weight );
names = dt << Get Selected Columns;
Show( names );
The above example is taken directly from the Get Selected Columns entry from the Scripting Index.
Help==>Scripting Index
Jim