After reading the suggestions I came to such a method:

1. Create a mintable Nxt subcurrency and let people mint as many coins as they can within 24 hours.
2. Create a special Bitcoin address and let those who took part in the previous step send several satoshis to back every minted coin.

These two simple steps solve sockpuppet issue (because resource testing is used), greatly reduce number of script kiddies (or school network admins) with botnets (because minted coins must be backed by bitcoins) and reduce advantage of being a Bitcoin early adopter (because minting requires a lot of GPUs and ASICs can't be used for that).