Like Jake points out we would need to win 3 more than Cas.
So with 10 games to go we would need to win at least 6 (And hope Cas lose all of those) from Bradford/Wakey/Saints/Salford/Leeds/Wigan/Catalan/Crusaders/Cas/Warrington (I can see 4 or 5 wins from those)
To stay in the 8 we also need to keep getting better results than Rovers/Bradford & Salford
Rovers have Wire/Quins/Wakey/Crusaders/Salford/Hudds/Bradford/Saints/Catalan/Cas (Possible 5 wins i would say)
Bradford have Hull/Leeds/Cats/Cas/Hudds/Wire/Rovers/Wigan/Crusaders/Wakey (possibly 4 wins)
Cas have 4 or 5 games against teams in the bottom 6 so the odds of us catching them are slim to none. So 8th really is the best we can hope for