Flatten Query Result Rows Into Columns with Comma Separted Values

I have this query:

SELECT 
    HICNo
    ,trr.CUS_ID
    ,TRRRunDate
    ,trr.LastName
    ,trr.FirstName
    ,trr.TRCCode
    ,trr.TRCDescr
    ,trr.TCCode
    ,trr.TRREffDate
    ,PBPID
    ,PriorPBPID
    ,LISLevel
    ,[LIS%]
    ,LISEffDate
    ,CONVERT (CHAR,INE_EV_DT,101) AS EventDate
    ,INE_USER_ID AS UserID
    ,tcl.TCL_TYPE_DESC AS [Description]
FROM 
    #AM_TRR_INS trr                                          
    JOIN ETLStaging.dbo.INS_INSURED ins ON trr.CUS_ID   = ins.INS_CUS_ID
    JOIN ETLStaging.dbo.INE_INSURED_EV ine ON ins.INS_ID = INE.INE_INS_ID
    JOIN ETLStaging.dbo.TCL_TYPE_CD_LOOKUP tcl ON 
            ine.INE_TYPE = tcl.TCL_TYPE_CODE
            AND tcl.TCL_ID = '12'
UNION 
(
    SELECT
        HICNo
        ,trr.CUS_ID
        ,TRRRunDate
        ,trr.LastName
        ,trr.FirstName
        ,trr.TRCCode
        ,trr.TRCDescr
        ,trr.TCCode
        ,trr.TRREffDate
        ,PBPID
        ,PriorPBPID
        ,LISLevel
        ,[LIS%]
        ,LISEffDate
        ,CONVERT (CHAR,INA_PRC_DT,101) AS EventDate
        ,ina.INA_USER_ID AS UserID
        ,tcla.TCL_TYPE_DESC AS [Description]

    FROM 
        #AM_TRR_INS trr                                          
        JOIN ETLStaging.dbo.INS_INSURED ins ON trr.CUS_ID   = ins.INS_CUS_ID
        JOIN ETLStaging.dbo.INA_INSURED_AUD ina ON ins.INS_ID= ina.INA_INS_ID
        JOIN ETLStaging.dbo.TCL_TYPE_CD_LOOKUP tcla ON 
            ina.INA_TYPE = tcla.TCL_TYPE_CODE
            AND tcla.TCL_ID = '12'  
)

That returns a result set like so

9876543A 123456789 02/13/2011

LASTNAME FIRSTNAME 011 Enrollment Accepted as Submitted 61 03/01/2011 002 开发者_Go百科 NULL 02/04/2011 MARKW APPLICATION 9876543A 123456789 02/13/2011

LASTNAME FIRSTNAME 011 Enrollment Accepted as Submitted 61 03/01/2011 002 NULL 02/08/2011 MARKW NEW ID CARD 9876543A 123456789 02/13/2011

LASTNAME FIRSTNAME 011 Enrollment Accepted as Submitted 61 03/01/2011 002 NULL 02/08/2011 MCSB473 INFORMATION SENT TO CMS 9876543A 123456789 02/13/2011

LASTNAME FIRSTNAME 011 Enrollment Accepted as Submitted 61 03/01/2011 002 NULL 02/08/2011 MCSB475 REPLY RECEIVED FROM CMS

I'm trying to flatten the results down to one line where the EventDate, UserID and Description columns are comma delimited and the results fit into one row and just using GROUP BY to flatten everything. I'm stuck- using XML PATH and COALESCE aren't working how I'd hoped...

It´s also possible to define your own aggregate function using CLR integration in SQL Server 2005, http://dotnetslackers.com/Community/blogs/basharkokash/archive/2008/06/07/how-to-implement-your-own-aggregate-function-in-sqlclr-sql-server-2005.aspx