Michael,
I flushed my brake fluid last weekend and here are my experiences.

1.  Pressure bleeders.
Volvo recommend using pressure bleeding to flush the brake system instead of the old and tried "pumping the brake pedal" method.  So I needed a pressure
bleeder.
There are two on the market for non professional users.  Motive Products sells a power bleeder that looks very good a has excellent reviews.  The price is US$45 plus shipping to Canada US$25 for a total of US$70.  The deal will be sweeter if you pick two one litre cans of ATE Super Blue brake fluid for US$10 each.

IPD sells a similar pressure bleeder for US$26 plus US$14 shipping for a total of US$40.  Not bad but the bleeder is not as highly rated as Motive Products offering and does not look too sturdy either. At the end I decided that I would beat both of them on price and features and built my own pressure bleeder.

2.  Home made pressure bleeder  (see the attached sketch).
I picked a 1 litre Nalgene bottle, made of HDPE, for CAN$6 (US$4), got a few feet of polyethylene and vinyl tubing, and nylon fittings for CAN$4 (US$2.5), picked up an old Volvo cap for brake fluid reservoir for CAN$1 (US$0.65) at a local wreck yard.  The total material cost was CAN$11 (US$7.15).  I glued the fittings to the caps with epoxy glue, attached the tubing and tested the set up at 35 psi using a bicycle pump.  Worked as planned.

3.  Brake fluids
Volvo specifies DOT4+.  I could find it only at a Volvo dealer and as usual they wanted far too much money for far too little.  So I got ATE Superblue for half the price and because the fluid is blue you can see it very well when it is coming out the bleed nipples.

4.  Flushing sequence
In one posting it was suggested to go:  RR, LR, FR, FL, another one was: RF, LF, RR, RL.
I don't think the order is that important.  I went:  RR, LR, RF, LF twice.

5.  Draining the master cylinder reservoir.
I found postings that suggested sucking the old fluid from the reservoir (tank) with a turkey baster.  Well, it is totally unnecessary.  The tank is attached to the master cylinder with a single 25 mm torx screw.  I removed it and lifted the reservoir.  The tank has two check valves at the bottom so there is no danger of splashing the fluid all over the place, but since it dripped a little a paper towel worked great.  A word of caution here; the check valves are hanging down from the openings, pushing them up opens the flow and the fluid is coming splashing down, so do not touch them unless you want to drain the fluid from the reservoir.  After taking it to a safe place I pushed the valves up, drained the old fluid, and then rinsed the reservoir with a fresh one.

6.  Flushing the brake system.
I reinstalled the reservoir on top of the master cylinder and filled it up with fresh brake fluid, attached the modified Volvo cap, closed the bottle and pressurized it to 25 psi.  I did not put any fluid in the bottle although it is designed for that purpose, but I wanted to check if the reservoir full of fluid would be sufficient to flush the system.  It was. The volume was enough to flush all four wheels once and the level in the tank never dropped below minimum.  I depressurized the system, refilled the reservoir up once more, pumped the pressure to 25 psi and went through all four wheels once again.  Total time was 1 hour, and 750 ml of ATE Superblue.

7.  One last note.
At the end I did not use my pressure bleeder for anything other than air tank although it was designed and built to work as a classical pressure bleeder.  So in the end one could possibly get an old cap, attach a length of hose and pressurize the reservoir using a spare tire or any other source of 25 psi air and I'm sure it will work too.

I hope you will find the above helpful.
Thank you,
Janusz

• More on the 850 brake fluid replacement procedure

• Why it is good to change brake fluid

• torque settings for brake nipples?

• a generic article on DOT brake fluids

• discussion on brake bleeding here amongst pad/disc replacement talk