How to pass param of size more than 8000 char to a storedprocedure thru ADO.

[[1998]Gopakumar VR Namboothiri]

I have a stored procedure in SQL Server with only one param of type
XML and expecting large data say 100k->2MB.
But the Command->Execute is throwing exception when the size exceeds
8000 characters.

Code = 80040e21,Code meaning = IDispatch error #3105,Source =
Microsoft OLE DB Provider for ODBC Drivers,Description = [Microsoft]
[ODBC SQL Server Driver]String data, right truncation.

I tried it with varchar(max),ntext.. on SQL server 2000,2005 and 2008
with AppendChunk on Parameter. All throwing exception..