You can use the same Carbon endpoints you already use to send tagged metrics. All you need to do is include the tags and values in the updated Carbon line protocol format (unix timestamp is optional):
my.series;tag1=value1;tag2=value2 metric_value (timestamp)
E.g. to get started quickly you can use the netcat utility as follows:
echo "YOUR-API-KEY.foo.bar;tag1=value1;tag2=value2 1.2" | nc carbon.hostedgraphite.com 2003
Sending metrics in your favourite language is similar. Refer to our language guide.