Use google maps and find a pair of dates when you want to travel to and from Bali, LAX-DPS, (Filter airline to Eva Air).
Once you find dates, then switch to multicity, keep the departure date (LAX-TPE-DPS) you found above, and return date you found above, but change return to TPE-DPS. Then, add another leg DPS-TPE somewhere in between these two dates, and see how much it prices. Keep changing the dates for DPS-TPE until you find a fare you are comfortable with.
then replicate this on EvaAir website, or use third parties such as Kayak/Expedia etc.