Byonics sells various cables for this application. Copied here for reference purposes are some notes from the Byonic page and also diagrams.

Yaesu FT-90
This 18-inch cable will connect a TinyTrak3 to Yaesu Mobile radios with a 6 conductor RJ-11 microphone jack. When used with the TinyTrak4, JP8 should NOT be jumpered on the PCB. When used with the TinyTrak3+, R8 should NOT be included on the PCB. This cable is available with a cigarette lighter plug or an Anderson Powerpole.