In 1858 the lower house of the Louisiana legislature authorised the importtion of "apprentices" from Africa in an attempt to circumvent the ban. The upper house of the Louisiana legislature defeated the bill.
Delegates to the Commercial Convention in Vicksburg in 1859 called for a repeal on the ban on slave imports. While not members of the US Congress, this group represented signifigant and influential business interests in the lower south
The ban on the importation of slaves was repeatedly violated by the south in the 1850s. Charles Lamar and the schooner Wanderer, being one famous example.
Did it? Look up the history of a gentleman named Charles Lamar. Charles Agustus Lafayette Lamr to be precise, who ran slaves into the south throughout the 1850's. In 1858 his ship, the Wanderer, picked up 600 slaves in Africa and ran the 400 survivors into Georgia. The federal government got wind of it and filed charges against him in Savannah. A local grand jury indicted him for it and they were almost lynched as tools of the Northern abolitionists. He beat the charge, or got off with a minor sentence, accounts vary. In any case he was importing slaves...let's see...why, he was importing slaves 50 years after you said the slave trade ended. How about that? He must not have known about it.
And the confederate constitution still protected slave imports.