It is not possible, if not subclassing EntityFieldQuery, and overriding some methods.

The conditions that are added to an object of class EntityFieldQuery (e.g. a property condition) are added to an array.

  public function propertyCondition($column, $value, $operator = NULL) {
    // The '!=' operator is deprecated in favour of the '<>' operator since the
    // latter is ANSI SQL compatible.
    if ($operator == '!=') {
      $operator = '<>';
    }
    $this->propertyConditions[] = array(
      'column' => $column, 
      'value' => $value, 
      'operator' => $operator,
    );
    return $this;
  }

When the query is built, that array is then used in a loop similar to the following one (the code is present in EntityFieldQuery::propertyQuery()):

foreach ($this->propertyConditions as $property_condition) {
  $this->addCondition($select_query, "$base_table." . $property_condition['column'], $property_condition);
}

$select_query contains the value returned from a call to db_select().

You can sublass EntityFieldQuery and override some methods.

The conditions that are added to an object of class EntityFieldQuery (e.g. a property condition) are added to an array.

  public function propertyCondition($column, $value, $operator = NULL) {
    // The '!=' operator is deprecated in favour of the '<>' operator since the
    // latter is ANSI SQL compatible.
    if ($operator == '!=') {
      $operator = '<>';
    }
    $this->propertyConditions[] = array(
      'column' => $column, 
      'value' => $value, 
      'operator' => $operator,
    );
    return $this;
  }

When the query is built, that array is then used in a loop similar to the following one (the code is present in EntityFieldQuery::propertyQuery()):

foreach ($this->propertyConditions as $property_condition) {
  $this->addCondition($select_query, "$base_table." . $property_condition['column'], $property_condition);
}

$select_query contains the value returned from a call to db_select().