If you're specifically referring to Cyber Warfare Engineer (designator 1840), I believe a couple (literally, one or two) slots are now available, but I will defer to current 1/C for that gouge.
1840s are still officers and will lead military and civilian development teams, but will also personally develop software and toolkits for operational use by the Cyber Mission Force and Cyber Protection Force, working closely with Engineering Duty Officers and Acquisition Corps officers to push capability to the fleet. Look up recent news regarding the new Cyber Foundry at NCWDG.
Three possible paths to CWE, assuming direct accession 1840 is still very rare.
-Commission 1810/1820, lateral transfer without board action to 1840.
-Commission SWO-Option 1810/1820, lateral transfer after administrative board to 1840.
-Commission any URL/RL, lateral transfer after administrative board to 1840.
CWEs are not eligible for command (any command, sea or shore) which is not in keeping with the whole "highest responsibilities of command..." part of the USNA mission. Lateral transfers without board action from 18XX designators are possible. All other designators will follow traditional lateral transfer process.
Probably the most feasible path is to major Electrical, Systems, Computer Engineering, Computer Science, Information Technology, or Cyber Operations, and aim for 1810. Following initial tour at one of the "Big 5" NIOC/FIOCs, shoot for follow on assignment to NCWDG or an NST to build the requisite technical skills for a lateral transfer to 1840. You need to prove yourself to get the chain of command endorsement and have the skills to pass the Fleet Cyber/Tenth Fleet screening during that first or second tour. The screening involves whiteboarding algorithms and psuedo-code/actual code, and will test understanding of development along the full network stack. Civilian equivalent would be something like landing a job as a Facebook/Amazon/Apple/Microsoft software/network engineer right out of college. The Navy used to exclusively recruit experienced developers from industry to make CWEs out of ODS. You gotta be good. Folks making it to 1840 right out of USNA are likely top of the class and in one of those six majors.
If you're referring to Information Warfare Community, slots are available every year for Cryptologic Warfare (1810), Information Professional (1820), and SWO-Option Intelligence (1830) or SWO-Option Meterology (1800) without being medically disqualified (including colorblind). Medical DQ personnel will have to option to commission into 1800/1810/1820/1830 after a screening process. All of these commissioning options are extremely competitive. Again, you should major in EE, CE, Systems, CS, IT, or Cyber Operations for 1810/1820. Political Science, English, and History are common majors for Intelligence, but it can vary. Oceanography is pretty much the only option if you want METOC.