I believe SSL2 is actually off by default.
See:
http://docs.sun.com/app/docs/doc/819-0986/6n3chgltn?a=view
If it's on in your case, LDIF to disable it:
dn: cn=encryption,cn=config
changetype: modify
replace: nsSSL2
nsSSL2: off
-
Then, restart your server.