I'm seeing the same (?) issue on Centos5, ruby 1.8.5 (2006-08-25) [x86_64-linux].

./S3_s3sync_mod.rb:119:in `verify_mode=': undefined method `verify_mode=' for nil:NilClass (NoMethodError)
        from ./s3try.rb:49:in `s3trySetup'
        from s3sync.rb:102:in `main'
        from s3sync.rb:721


I fiddled with SSL_CERT_DIR and SSL_CERT_FILE to no avail.