Live analysis requires special precautions when decapping. As I write this, I have done very little, and this is probably beyond me. Nonetheless, I will maintain this so that when I have more experience, the material will be available.
Chose a decapping technique that will preserve the bonding wires. In particular, you probably want to do a nitric acid etch that has been diluted with sulpheric acid. A probing station using micropositioners/microprobes would probably be ideal to probe the pins.

====== Probing station ====== 

Integrated setup with a variety of components

====== Washing ====== 

Standard live analysis method involves dropping hot RFNA or plain nitric acid on a milled out cavity onto hot chip. The mixture should never be allowed to get dry. Wash out cavity with acetone (DO NOT USE ALCOHOL...boom). While squirting is easier, it tends to dislodge bond wires. Instead, swish it around in a dish. Use 9 parts 70 % nitric : 1 part 98 % sulphuric to improve copper's resistance.