Not sure if you're still looking for an answer to this or not... I was given this same make/model of microphone too. The 4-pin connector is confusing because it comes from a time when connectors weren't as standardized, so it has several names and lots of uses. It's sometimes known as an Amphenol, MC-M4, and/or CB connector. Manufacturers often used it for various applications, so the pin out was never standardized.
The DM-58 HL I was given came with a matching female 4-pin to male XLR cable. It was wired like this:
G + –
4-pin 1 2 3 4 (not used)
XLR 1 2 3
The good news: If you have $5, a few minutes, and some soldering know-how, you can make a cable to fit this mic.
You can find the 4-pin connector part you need at Radio Shack.
4-Pin Female CB and HAM Radio Microphone Plug
Catalog #: 274-001 4-Pin Female CB and HAM Radio Microphone Plug : Microphone Plugs | RadioShack.com
The switch on the side of the mic changes the output from high to low impedance. Once you have the cable wired up to XLR, you'll hear right away which setting is which and sounds best.