OK i have posted this before a while ago but it was maybe a bit complicated. And since Blizzard implemente some new macro features i could make it simpler!
OK first off open your macro window (/macro) and create a new macro.
Now just put this in the macro
/use Big-mouth Clam
Just change the clam name to the ones you are grinding. When you click the macro it will just open the macro (not loot it) So now go to your interface options and check the box that says "auto-loot" so now when you cick the macro it will open'n'loot the clam for you.
Now just go to Glider config and deselect the box that says "shift to loot".
Now put the macro on your interface and bind a key to it. Open uo your keys.xml file (go to glider config ans then the keys tab and click save if you dont already have a keys.xml) Open up your keys.xmlin notepad or something and look for "post loot" in the common section. Now just enter the key binding for the macro. (if you lag just put it in the pre combat section)
there you should be all done
Hope that was simple