Go to the BOINC website. They have a FAQ for this, last I checked. They WANT your project to use the BOINC client, so they'll assist you, if you ask on their forum. How much, I'm not aware of. Checking with any similar BOINC project, might also help.
Naturally, you'll need some sort of a PC to act as a central collection server - something where the results can be turned into, and something like 1 to 10 points per hour of computation time, can be awarded, and the data updated to show the current status of the search.
Since computers can make errors, it's necessary to have the calculation of each digit checked with the actual value of Pi, digit by digit. Easy enough for a little program to do that.
For the calculation of Pi itself, I'd check with any comp.sci or comp.sci.math newsgroups or forums, and of course, Google. I ran a (singular) homegrown effort on Pi several years back, but my expression for Pi converged much too slowly. Keep in mind that with a poor expression, you can calculate with it for an entire week, and gain less than you would in 2 hours, if you had a much better mathematical expression, on the same hardware.
You want to use a fast expression to converge on Pi, and you want to use a fast "core" program to run that expression. A client program (which can be quite slow, it doesn't matter), will handle the communication with the server (sending in the results), and starting and stopping the core program, as well.
Make sure that your Pi program runs in low priority. If it runs in normal priority, it will simply annoy people who want to use their computers for gaming and other high intensity programs, and won't be able to use all their PC resources.
It would be nice if it could run multiple threaded instances of itself (the client program would handle setting that up), since so many PC's now have multiple cores.
What I'm not sure of, is whether searching for digits in Pi, can be run "independently" - that is, in "parallel", where Bob can run calculations for the first 1000 digits, and Charles can run the second thousand digits, and Ed can run the third thousand digits, and they can all be running at the same time. Specifically, that Ed won't have to wait for Bob and Charles to finish up, before he can begin his calculations. If the calculations have to be run in sequential mode like this, it really cuts down the speed of the whole project, (but it may be even more fun).
The worst thing would be a substantial 'bottleneck" member, on a sequential project. Maybe he/she is running it on a really slow tablet or laptop, or only running it a few hours each week - that would surely kill the project's forward progress, pretty quickly.
BE SURE AND KEEP MULTIPLE BACK UP'S of the data, and any points awarded! You can bet that serious problems will arise eventually, in any serious project.
I just popped over to the BOINC site here:
http://boinc.berkeley.edu/trac/wiki/VolunteerComputing
which had some interesting info, but not the FAQ I had seen way back when.
There are other ways to run a distributed project than with BOINC, so don't hesitate to contact people like CERN's Grid Cafe, Great Internet Merseinne Prime Search, or Folding@Home people to see if they can assist. University comp.sci or math people may be another resource you can use.
Good luck with your project. You may want to use this forum as a central "info" sharing site. You never know, you might get some volunteers even.