I saw the tanslation of Mea Culpa. I really liked it. Perhaps I can help you with the meaning of "Prend Moi" the way I see it, and correct me if I am wrong.
In the context of that song a person is admitting being some kind of culprit in what seems to be the culmination or paroxism of mutual passionate feelings. These feelings have probably derived from a simple friendship and have grown to the point that neither beings dare taking responsibility to jump into a loveship in the threat of loosing a beautiful frienship. We all know the pressures of love are much more grand than the one of friendship.
It finally overcomes one of these people. So I guess one of them decide to assume the burden of carrying the relationship into loveship. This same person in effect acknowledges future responsibility in the event that the loveship will ultimately destroy the friendship (at the point where "Mea Culpa" is spoken).
"Prend Moi" (which means take me in the sense of "Make love to me, I am ready now!").
"Mea Culpa" is basically saying: "Blame it on me if we'll loose everything because of me giving you now the green light"
I suspect that Thierry Lockner's analysis is a little more light than the song deserves. Here's a somewhat darker interpretation.
Mea Culpa in the context of the full album MCMXC a.D. can be seen as a speech of submission -- maybe to Sade, or someone like him. Sex in this context may be the "interdit" sex of dominance and submission -- the slave says to her master, "I want all, when you will, as you will." It is the ultimate surrender: "Je m'abandonne."
Finally, this idea is a little more far-fetched, perhaps, but I think that "Je suis la et ailleurs" may refer to the "out-of-body" sense that one may occasionally achieve as a result of some of these practises...
"Mea culpa" is a slightly more precise phrase than "I'm guilty", although the latter translation fits well in the context of the rest of the lyrics. At that, "I'm guilty" is a lot closer than "it's my fault". "Mea Culpa" translates literally as "I am culpable", having altered very little in it's journey into the English language. The concept of culpability is one almost entirely separate from that of guilt - culpability has to do with being responsible for something which may or may not be under your control. You are (legally) culpable for the actions of your minor children, if they cause damage to the property of another person. Nobody claims that you are guilty of your child's crime, simply that it is your responsibility to pay for the damage.
More accurate translations in the context of the lyrics would be "I take responsibility for this" or possibly "blame me".