I must admit I have not had to do a blower yet, but I have torn down a 240 dash or 2. There are really not that many bolts to take out if you know where they are. You only need a phillips and torx head screwdriver (The Volvo tool kit screwdriver has them both) and a few sockets (probably 11 to 13mm). Other than that you just have to unplug wiring, and most of the connectors are unique so you don't have to keep track of where they go (just mark the single wires).
So I would probably take the dash apart rather than trying to piece back together a butchered blower housing. That way you can comfortably sit in the drivers and passenger seats while you work on the blower, rather than cursing and swearing while hanging upside down under the dash hacking a hole in the blower housing.