How do I change the config path for mysqld?
You need to use the --defaults-file option as follows

mysqld --defaults-file="E:\\db\\my.ini"


or

mysqld --defaults-file="E:/db/my.ini"


If you are running MySQL 5.6 already on the Windows machine and you are trying to run an additional MySQL 5.6 instance, make sure you change the following under the [mysqld] group header in your my.ini


the port number (other than 3306)
datadir (such as E:\db)


perhaps like

[mysqld]
port = 3307
datadir = "E:/db"


Give it a Try !!!