- Go to Endnote styles page and download the styles you want.
- Open Zotero and open the preferences pane, choose Styles from the icons at the top
- Click the + button at the bottom right corner
- A window appears allowing you to select and import the style from wherever you just saved it
It should then appear in your style list. I just did this for BMC Evolutionary Biology which you can see in the window screenshot given here. I haven't yet investigated whether you can batch import files.