If you have some French knowledge already, it should be fairly easy for you to pass the reading comprehension and writing tests at B level after a couple of weeks/months' preparation. (For the reading test, you need only score 38 out of a total of 65 multiple choice questions to get a B, and for the writing, 31 out of 55.)
The oral interaction will be more difficult, but I think you can do it if you have the determination to master the language (just think of it as one of the many programming codes/scripts you have to deal with in the IT field!). There are many advantages for you to become officially bilingual -- eg other job opportunities will come up, this particular position may not be filled by a permanent employee for the time being and may be open for competition again etc. You never know.
Besides, the French language happens to be one of the most beautiful languages in the world -- you won't regret learning it, as your life will be enriched by your access to another great culture. Bonne chance!