Use a NPN transistor, drive the base with a resistor , emitter to ground, led cathodes to the collector and the anodes through resistors to the positive supply.
hello
it will be difficult with only one pin of microcontroller !
Maybe you can search on the web One Wire bus system ..
but with 2 pins, you can use I2C interface (2 pins: SDA SCL) or SPI interface mode
with one MSP23017 to drive 8 or 16 outputs .. and add a buffer like ULN2083 for more current in leds.