How do I ensure same session over multiple statements??

To all,

I have a situation where I need to issue the following:

set enable_nestloop = off

before executing a prepared statement. We are using connection pooling.
m_conn is a connection object that is retrieved earlier in the code.

Code fragment....

PreparedStatement ps = null;
ResultSet rs = null;

try
{
NEED TO DO THE SET HERE
ps = m_conn.prepareStatement(
"SELECT t1.id, t2.md5, t2.url from referral_temp t2 LEFT
OUTER JOIN d_referral t1 ON t2.md5 = t1.referral_md5" );
ps.setFetchSize( T_FETCH_SIZE );

rs = ps.executeQuery();

WHEN I AM DONE LIKE TO REVERSE THE SET

.......

I can do this just fine through psql since I am always in the same
session. How would I do that given the above code fragment?

Thanks.

--sean