First of all, ignore the old wives tales... if we listened to every old wives tale then we'd never do anything!
Second, yes it would be a good idea to get paws used to the fact she's not the most important thing in the house anymore. Getting OH to bring home a blanket that smells of baby is a fab idea - she'll get used to the smell pretty quickly. Also, when you bring baby home, put something of yours in the carseat with them so that the baby smells of you. You're already one of the pack so if something comes into the house smelling like one of the pack she'll be more inclined to accept her.
If you can, get hold of some Feliway or Rescue Remedy (they do a version for pets without alcohol). It'll calm paws down as she'll naturally get stressed.
This is easier said than done, but when you first come home, let OH carry the baby in the carseat, YOU go straight to the cat and give her some fuss and attention. Try and keep a good level of interaction with the cat so she doesn't feel pushed out.
She will be naturally curious of the strange thing in the moses basket - if she comes over, don't shoo her straightaway - watch her closely but let her have a look at the baby. Chances are she'll be scared of the baby as cats dont like things that are unpredictable (and a baby is very unpredictable!) If she tries to climb in the moses basket, discipline her how you usually would (one of ours gets a firm no, the other one gets shouted at as he's a bit dim!) and put her out of that room for half an hour. Cats HATE being ignored so being barred from a room while your in there is a punishment.
Before bubs arrives, close the door to the nursery and your room (as bubs will be in your room at first). This will get the cat used to the fact that certain rooms are out of bounds now. As soon as bubs is in her own room, the cat can be allowed into your room again (if you like that sort of thing, I love having a feline waterbottle on my feet!)
When bubs isn't with you, the cat may come up to you for fuss and attention. As long as you haven't got hold of the baby, go for it! Same goes for your partner, if he doesn't have the baby then there's no reason why the cat cant have a cuddle. Cats are very adaptable, and you will probably find as the baby gets older the cat switches allegiances and becomes the baby's cat, rather than yours! They are also very loyal creatures and once they realise that this is your baby they'll become very protective of her.
She will be put out by the new arrival, but try and reassure her as much as possible that she hasn't been replaced. She'll also be curious of the baby's things, let her have a look at them, but make sure she knows her boundaries (i.e. the moses basket and pram are not her new beds!).
That turned into a bit of an essay but if you need any more help, feel free to ask. I have 2 very pampered paws and were getting them ready for the baby arriving now.