So I've been reading about blind signatures on wikipedia and...
phpseclib already does blinding to an extent when it's doing it's modular exponentiation. Both RSA blinding and blind signatures require the random value to be relatively prime to the modulo. phpseclib uses a the chinese remainder theorem to do the exponentiation on p and q instead of N and to sorta combine them and since p and q are prime anything less than p or q is trivially easily relatively prime to them.
Unfortunately, this technique doesn't work for blind signatures since, with those, the person doing the initial blinding would only have access to the public key.
Anyway give me a few days and I'll try to whip something up as time permits.