At the moment, zero. I know only the most basic words and phrases. So it would need to begin at a very basic level and then build to the level needed for authors like Huysmans, Baudelaire, Balzac, etc.
That's ambitious! I'm certainly not even close to that proficient after going through all of school with it, but I do enjoy Duolingo for a good balance of brushing up on reading/speaking/listening skills. I'm not sure it does a good job teaching grammar, though.
I don't speak any French, but I do teach Spanish (which I started learning at age 19) and I can get by in Italian after a few semesters back in college, so my advice is more about learning languages in general than about French. First off, I think your effort and the time you put in is more important that the software you pick.
Since learning a language is a lot more like learning a new instrument than learning stuff in history class or something, it's all about how much you practice so your brain can start working out those new pathways. I think just about any respectable language learning program would be a good start. Duolingo, Rosetta Stone, etc...
But when going for the proficiency you're seeking, you'll have to go beyond the practice those programs offer. In commonly taught languages, like French and Spanish, you'll be able to buy bilingual short story books, which will give you a good examples of quality fiction, with the original French and an English translation in the same book.
You'll need to get some basics under you first, but struggling to understand those texts will be worth it, but my general rule of thumb is if you have to look up more than a couple words a sentence, you're not ready for that text yet. However, if you work your way through something hard, you'll at the very least be better at the end and understand more than you did at the beginning.
I have a used copy of a Gabriel García Márquez novel (in Spanish) where on the first page there are English translations of 3-4 words on each line. The translations suddenly stop early in the second page, where the person obviously gave up in frustration. You always want to be challenging yourself, but if the gap's too big it will just be frustrating.
So, the short version is- pick something to start the basics and put a lot of work in, then push yourself into other things. Also, watch lots of French TV/movies, listen to podcasts and radio, to train your ear. There's no shortcut to getting better at listening- just lots and lots of listening.
Thank you @BjorgenFjorgen! @LeSamourai thank you for the very detailed response. You make so many good points and I appreciate you taking the time to share your experiences and advice. I feel that I will mostly spend the first year becoming mildly proficient in conversational French...
This would be at 5-8hrs of study per week from what I gather. I know the actual reading comprehension and translation will be a multi-year endeavor. However, many of my favorite authors' original works are in French so I would really like to explore their offerings in their original format.
Plus, if I ever plan to go back to school and obtain a graduate degree in literature, proficiency in reading and translation of a foreign language is almost mandatory.
Another point about speaking, it helps immensely if you have someone to talk to in that language! My sister is a French teacher and her husband is French-Canadian so I get way more practice now talking to them and their 2-year-old daughter than I ever really did before. Not to mention a better reason for wanting to learn it. Good luck!