I'm sure it can be done in PHP, but it could be a little slow (and it will spike the CPU as it's going to have to plow through some possibilities to check).
I have the links to the instructions at home, though, so I will try to get those to you this evening. The general idea, though is to take the DV number (create it from the IVs, see xacts article) and then to basically use this as 1/2 of the seed and then plow through all 65536 combinations of the first part, using each one to seed a reverse RNG to get the PID part until you find one (or more) with the same nature. At least this is what gathered I was going to have to do from a quick skim of the articles that I read.
Next for each match you start going backwards through the sequence looking for possible matches based on the formula for platinum seeding and present the probable candidates to the user.
Fun stuff and I think the result will be pretty fucking awesome.