How to Install an ATtiny Bootloader With Virtual USB
Contributors:
Shawn Hymel
Shawn Hymel 
Resources and Going Further
While this is a lot of information to take in, it shows how to hack the Arduino IDE to load custom board definitions. These steps should work for other ATtiny devices that are supported by the micronucleus project, such as:
You might have to modify the pins_arduino.h file, however, if you plan to use a different ATtiny.
ATtiny84 Pinout
If you need additional support, please check out the following resources.
If you want to go further with the ATtiny, please check out our additional tutorials that showcase the ATtiny:
Firefly Jar Assembly Guide
Make a soft circuit firefly jar with conductive thread, LEDs, and the LilyTwinkle!
LilyTiny Plush Monster
Craft a stuffed monster while exploring the LilyTiny preprogrammed microcontroller. This is a project based on the Plush Monster Activity created at MIT's High-Low Tech Lab by Emily Lovell, Jie Qi, and Natalie Freed.
Light Up Pennant with E-Textiles
Show your school spirit, geek pride, or fandom with a light up pennant using the LilyTwinkle or LilyPad Arduino.
Night Sky Halloween Costume
Make a beautiful night sky costume using the LilyPad LEDs and the LilyTiny.