Do you have an ODBC driver and an ODBC connection pointing to your sharepoint list?
Do you have a JDBC driver?
If you don't have any of these ... OBIEE can't really help you: it needs a source it can connect to, and in general "exotic" sources uses ODBC.
Here you go. No clue which one works best but as soon as you can establish an ODBC to literally ANYTHING, then OBIEE can read it.
Edit: aaaaaaand obviously Gianni had his word to say while I was copying driver links
I don't have a ODBC driver, I do have a JDBC Driver, is there a way to connect using JDBC?