OK, this is how I do it.

I go to www.tabonline.com.au/2005/07/09/mtgraces.html
pick a race... for example Randwick race 4.
Hit race 4 and open race 4 page.
Near the top left corner are radio tab tips ( in this case 4,1,7 )
Take these Nos ( 4,1,7 )to win with the field to come 2nd in exacta and
take the field to win with 4,1,7 to come 2nd in another exacta.
I bet 50c units.

Thats it.

Yesterday, in racing, & trots ( i never checked the dogs but it should work there also ) it returned more winning exactas than there were races as in some you'll get the exacta twice. ie maybe 90 races and 90 plus winning exactas