The key is to lose your mind and all of your den space~ You'll ideally want 2-4 pairs (so 4-8 wolves total) that get you at least... part of the way towards your goal, and then plan on how to pair their kids to get you closer to it, until you get there.
So for your project, you'll want to start broad because there are just... not enough people on the site to sustain huge breeding pools and eclectic ranges, so the bloodlines that exist & are readily traded on the Flea Market are really samey in their given niche grayscale/brown ranges (for the most part). I'd begin by looking for a few unrelated 4x white dogs, since 3x white is what you're aiming for. Then look for anything with a belly in the toxic-butter range and try to find a few that have that trait. Bonus points if you can find some with some grayscale colors in at least one or two slots, or even some of the closer-to-black purples.
If you can't find any of those, sometimes you'll just have to overshoot what you want, sometimes by a large margin. So, for example, you may need to look at dogs with more orange/brown bellies than you really want as a starting point, and then work your way back up the yellows to blond during the rest of the breeding project to get all the other colors back towards white.
Then it's just throwing dogs from both groups at each other and seeing what sticks. You will produce a TON of extra dogs and failures in the process, unless you get incredibly lucky, so it helps with speed if you're cool with releasing a bunch. My den is always a huge nightmare of breeding projects, right now it's super full of red dogs for a blood/sand/blood/cherry project (for an ethiopian wolf OC), but my main perma den is mostly full of dogs that I've had to go on months long breeding projects to get. :P
It's worth it though! Bringing a new color combo onto the site is fun because it's a big challenge right now.
EDIT: You probably already know, but wolves also can't breed with things within 5 generations of each other, which means things get a bit fraught the fewer pairs you have. However, it does mean that if you CAN find enough starting pairs, sometimes you CAN get bloodlines looping back around again. It is definitely a kick in the pants for den space though, moreso than any breeding project already is. :S
