METAbolt is compatible with SL and all Grids that are based on OpenSimulator.
Select the grid of your choice from the dropdown box on the login screen and enter your username and password and login in. If the grid you want is not listed then select the "Other" option at the bottom of the dropdown box and the grid/server Uri into the Login Uri textbox which will be enabled to the right of the dropdown box.
You can get a list of available grids etc from:
http://opensimulator.org/wiki/Grid_ListInstructions on how to connect and information etc:
http://opensimulator.org/wiki/ConnectingThe Grids listed on the login screen are controled by the file named "Grids.txt" which in the Data Dir (use the About METAbolt window if you don't know where this folder is) folder. You can manually edit this file to include or exclude grids as you wish.
Click here for more information.