Ideally, you need to pull the dash to get the expansion valve out. This involves full dash removal including crash bar, HVAC box removal and disassembly.
HOWEVER, with a ton of patience, you can extract the expansion valve through the engine bay. It is an extremely tight fit though, and typically results in destruction of the foam seal around it.
To remove the valve through the engine bay, remove the 10mm nuts holding the suction and pressure lines to the valve where they enter the firewall.
Then remove the allen bolt holding the adapter block to the expansion valve.
Then remove the allen bolts holding the expansion valve to the evaporator.
The expansion valve must then be pulled off the evaporator, which is where you run into problems. The sealing orings are extra tight and give nowhere to pry them two apart. Furthermore the sealing foam helps hold it in position as well.
There really is insufficient room to do this with any amount of ease. It is something I have adapted from many many replacements; the proper and safe procedure is to remove the dash, to the tune of 7 hours in labor, unfortunately.