You'll need head light, tail light, turn signals, mirrors and horn.
I'm not familiar with the "DX"... I know about the DT which was street legal, and MX, which wasn't.
If the bike has a brake light switch on the brake pedal, and has the switch cluster on the left handlebar for headlight, turn signals and horn, then it won't be a big deal - the wiring harness should have the wires you need - otherwise you'll have to run the wiring yourself.
Also, if the bike has the switch clusters, they'll have threaded sockets for the mirrors.
Parts are getting scarce. You can usually find some stuff on eBay, but it's hit or miss with parts these days.
There is a place in North Hollywood called "Johnson and Wood" that has a pile of milk crates full of turn signals and mirrors, especially bunches of the old 6 volt stuff. But, YOU have to dig through the crates to find what you need.
http://www.yelp.com/biz/johnson-and-...orth-hollywood