GIVE ANSWERS - English

NOTE: I suggest Eglish language "neophytes" (ie, inexperienced) avoid such phrases as "down" or "to be down with", etc., it's not only "Ghetto" but in most instances it will simply sound/look silly. Just my two kopecks. Oh: you're Argentine, so instead "Just my two pesos."

Well, let's start by correcting your "question" (ie, request):

"Is this sentence written correctly?" OR "Have I written the following sentence correctly?"

Now, with that taken care of, let's look at your sentence, i.e., "I'm down to work anytime."

The precise meaning of your sentence, based on this syntactic structure, is not clear: do you mean to express that "I am available to work at any time?" If the answer to this question is "yes", then your sentence needs to be reworded thus:

"I am available to work anytime."

NOTE: Okay, so if this was your (original) intention, is the 'correction" clear? If not, shoot me a note (reply) here and I will (re)explain things for you.

PS: Since you mentioned "slang" in your title, I am wondering if what you are trying to express is that "I am ready to work anytime." with (what I call) "street" language, ala something along the lines of "Yo, I'm down with working anytime." = "I am available / willing to work anytime."

Maybe this ^^^ is what you intended?