According to opencv documentation,
Here is how to create a storage for various OpenCV dynamic data structures and fill a dynamically growing sequence :
CvMemStorage* storage = cvCreateMemStorage(0);
CvSeq* seq = cvCreateSeq( CV_32SC2, sizeof(CvSeq), sizeof(CvPoint), storage );
int i;
for( i = 0; i < 10; i++ ){
CvPoint pt;
pt.x = rand();
pt.y = rand();
cvSeqPush( seq, &pt );
}