Edit: Oh... BM?
http://www.wowwiki.com/Useful_macros_for_hunters#Spamable_Beast_Mastery_Hunter_Macro
There is a macro floating around somewhere online that makes keeping Serpent Sting up ROFLEASY, but it's unreliable and requires two separate macros to make it work right. You should get used to refreshing that manually.
Edit again: The shift key and punctuation are your friends.
Edited, Apr 14th 2009 6:52pm by Ayrii