gistfile1.js

> db.users.find();
{ "_id" : ObjectId("1145184c5f8f127526010000"), "script_settings" : { "b2460e4c73e106ba93010000" : { } }, "scripts" : [ "b2460e4ca68d0cba93020000", "b2460e4c73e106ba93010000" ]}
> db.users.update({_id : "1145184c5f8f127526010000"},                                                      
...                 { 
...                     $set : 
...                     { 
...                         "script_settings.b2460e4c73e106ba93010000" :
...                             { 
...                                 block : ["hi"]
...                             }
...                     }
...                 });
> db.users.find();                                    
{ "_id" : ObjectId("1145184c5f8f127526010000"), "script_settings" : { "b2460e4c73e106ba93010000" : { } }, "scripts" : [ "b2460e4ca68d0cba93020000", "b2460e4c73e106ba93010000" ]}