Help with partitioning an existing table

[Ravi Malghan]

I am a newbie to mysql db. I have a table that I have partitioned by a datetime field

create table status (
        SERVERSERIAL    NUMERIC(16) NOT NULL,
        SERVERNAME      VARCHAR(64) NOT NULL,
        FIRSTOCCURRENCE DATETIME NULL,
        CUSTOMER VARCHAR(64) NULL,
        <..many other fields>
        PRIMARY KEY ( SERVERSERIAL, SERVERNAME,FIRSTOCCURRENCE )
)
PARTITION BY RANGE COLUMNS (FIRSTOCCURRENCE)
(
        PARTITION p2012_3 values less than ('2012-09-30'),
        PARTITION p2012_4 values less than ('2012-12-31'),
        PARTITION p2013_1 values less than ('2013-03-31'),
        PARTITION p2013_2 values less than ('2013-06-30'),
        PARTITION p2013_3 values less than ('2013-09-30'),
        PARTITION p2013_4 values less than ('2013-12-31'),
        PARTITION p2014_1 values less than ('2014-03-31'),
        PARTITION p2014_2 values less than ('2014-06-30'),
        PARTITION p2014_3 values less than ('2014-09-30')
)

The table currently has 3Mil rows. I want to partition it further by customer since most of my queries also have customer name in the where clause. Have a few questions

a. I think I need to add the Customer field to the primary key. If so, do I need to suspend all writes to the database when I run the alter command?
b. can someone help with the alter statement for adding customer to partitioning in addition to FIRSTOCCURRENCE or some pointers?

Thanks
Ravi