The code sample below will show you how to create a GL Account in eConnect.
The code sample requires the eConnectHelper class, which can be found on the eConnect Index page
Here we use the GLAccountType and otaUpdateCreateAccountRcd nodes
Edit 1/9/13:
The documentation for this schema says that it will uset update whatever you send and that no parameters are required... but as far as I can tell, that's not true. You have to supply about 7 paramaters or it will error with a very odd error. See this post for details: http://dyndeveloper.com/thread.aspx?Threadid=834