I don't quite understand what you mean by "set-up". I simply save the peek in any random folder, and bring it up at a later time to use the packets I've already aqquired. There is a minimum amount of packets to be collected before you can attempt to crack the encryption. Make sure the WEP your cracking is 64 bit, or 128. Collect the packets, crack the encryption.
If you close the program without cracking, the packets you have already got are pretty much useless.