I had the old wallet too. You need to sync your old wallet and then save a copy of your wallet.dat (just in case). It should be in your apps/roaming folder. Then download and install the current paccoin wallet from paccoin.net, dont worry it wont overwrite your old wallet, it will just update it to the 'redemption wallet'. Your coins will still be there.

Now you have the updated redemption wallet you need to install and sync the new $pac wallet and just send your old pac to the redemption address and copy your new $pac recieve address into the appropriate field so they know where to send your new $pac coins to.