Audit Tables With Composite Keys

I am trying to write triggers on each tables in my database to audit data changes. My AuditLog table consists of the following columns -

LoginName varchar(100) - user name
Action varchar(5) - this will store 'INSERT','UPDATE','DELETE'
TableName varchar(30) - name of the table updated
PrimaryKey int - primary key of the record updated
ColumnName varchar(30) - name of the column updated
OldValue varchar(1000) - old value converted to varchar
NewValue varchar(1000) - new value converted to varchar
RecUpdDate datetime - record update date.

This table design will work for tables with single column primary keys. However, it will not work for tables with composite primary keys. Any suggestions on how to make this work with composite primary keys? I prefer not to change the tables in my database to use single column primary key.

Thanks in advance.