I know I'm reviving a bit of an old topic but I thought I'd post my work-around for this problem. So, I had problems with my tomb raiding sim being a girlie, maxed out in sim-fu and athletics. So, I had to resort to a bit of cheating for this. Mainly because I spent quite a bit of time wandering round from tomb to tomb trying to find a mummy I hadn't defeated.
So, whilst in Egypt, in a community lot (the tomb under the marketplace) I place a bunch of sarcophogi (used testingcheatsenabled true and buydebug) and ctr-shift clicked and set them so that the mummy 'always' comes out. Then I temporarily changed two of my sims traits to loser and unlucky. Following that I opened up all the sarcophogi and let her at the mummies. Well, she lost every single fight, which I was really chuffed about. However it took about 15-20 fights (lost count at one point) before she got cursed. Following that I deleted everything, changed her traits back, and happily went off to the sphynx
Took two sim days though in total just fighting the mummies.
[Edited for language. Please do not use profanity of any kind. -Pam]