How do I use ATTiny pin 5 (RESET) as a digital output? I am using an Arduino Uno as ISP (Using the standard ArduinoISP sketch) to program an ATTiny13A through the Arduino IDE. (I also have a USBtinyISP 2.0 and a USBASP 2.0, but can't reliably get either to program this chip with any sketch.)

I want to use all six I/O pins on the ATTiny to each control 1 LED. Pins 0 through 4 work fine, but since pin 5 is the RESET pin, it doesn't want to work as an output normally.

I have read from many sources that I can disable the reset pin by changing the fuse bits, and that once I do so I will not be able to program the chip any more. Every source I've seen has given this warning, but has then proceeded to NOT say how to accomplish the 1-time-write.

Assume I've got my sketch exactly 100% as I want it, don't have a high-voltage programmer, and am fine with only being able to program the ATTiny once. How can I program the chip and set the appropriate fuse bits with what I have access to?
RSTDISBL is bit 0 of the high fuse byte. Use avrdude to read the current value of the high fuse byte (-U hfuse:r:-:h), clear bit 0, and then write the value back out (-U hfuse:w:0xXX:m).