The trick is to concatenate the data series values into your pie slice label, as follows:
Example 1 for count
| stats count by opeTOM
| eval opeTOMSlice=opeTOM+ ": " + count + " Transactions"
| fields opeTOMSlice, count
Example 2 for total durations
| stats sum(Duration) as sumDurationSeconds by opeTOM
| eval totalMinutes=round(sumDurationSeconds/60)
| eval opeTOMSlice=opeTOM+ ": " + totalMinutes + " Minutes"
| fields opeTOMSlice, sumDurationSeconds
I haven't tried this myself, so it's a bit of a guess (someone else might give you a better answer), but have you set the layoutSprite properties to
visible in the XML?
The tool tip properties (http://docs.splunk.com/Documentation/Splunk/4.3/Developer/CustomChartingConfig-Tooltip) inherit from layoutSprite.