"I can't imagine how this could possibly go wrong"

or

"I can't conceive how this could possibly go awry"

Hi erik_the_bard-ga -

You came up with an interesting quote.  It shows a lot of confidence! 
The most accurate translation I can give you is this:

    "Animo concipere non possum quo palto hoc pervease exeat."

When rendering your phrase, I followed Latin usage,  so  the literal
translation is this:

    [I can't conceive under what conditions this could possibly end badly.]

I did consult with a Latin scholar to make sure that the translation
is idiomatic and correct, and I used Cassell's Dictionary.

   Cassell's  Latin-English and English-Latin Dictionary revised by
J.R.V. Marchant, M.A. and Joseph F. Charles, B.A., Funk and Wagnell's
(New York)

http://www.powells.com/cgi-bin/biblio?inkey=1-0025225804-12  (latest edition)

Here are some websites that may be of interest to you:

Latin proverbs and locutions
http://leptir.ifs.hr/~mpinter/proloc.html

Latin phrases used in English
http://www.math.ohio-state.edu/~econrad/lang/lphrase.html

Enigman's favorite Latin sayings
http://members.ozemail.com.au/~enigman/latin.html

All the best,

alanna-ga

Very helpful. Well explained.