How to override lookup in Ax2009?

Write following method on form level

void SummaryProjectLookup(FormControl ctrl)

{

SysTableLookup sysTableLookup = SysTableLookup::newParameters(tableNum(ProjTable),ctrl);

Query query = New Query();

QueryBuildDataSource queryBuildDataSource = query.addDataSource(tableNum(ProjTable));

QueryBuildRange queryBuildRange;

;

sysTableLookup.addLookupfield(fieldNum(ProjTable, ProjId));

sysTableLookup.addLookupfield(fieldNum(ProjTable, Name));

sysTableLookup.addLookupfield(fieldNum(ProjTable, Status));

queryBuildRange = queryBuildDataSource.addRange(fieldNum(ProjTable, Type));

queryBuildRange.value(queryValue(ProjType::DEL_Summary));

sysTableLookup.parmQuery(query);

sysTableLookup.performFormLookup();

}

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public void lookup()

{

element.SummaryProjectLookup(this);

}