Since you have a cracked copy, the only think I can suggest is searching around for 1.8.1 cracked clients, but keep in mind warez is not allowed in public forums.
If you have AIM SKYPE or MSN I could add you and send my copy to you, Since I'm technically passing around warez but on the forum. Therefor I'm still legal :3
You could:
1) Ask to borrow an account
2) Get an auto-updating cracked client from premium
3) Buy the game
4) Get someone to give you their minecraft .bin folder