Chunghwa has responded to Vibo’s offering prepaid 3G. If you have a 2G Chunghwa prepaid card, just go to a Chunghwa office and ask for a 3G prepaid USIM (which requires a 3G phone, of course). By swapping the SIM for a USIM, you’ll not only have internet access on your mobile phone, but can tether it to a notebook PC (assuming you have the right cable, drivers, and incantations). It takes a day or two for the network provisioning, so the Chunghwa rep will give you a 3G card and tell you what date to swap the 3G USIM for the 2G SIM. There’s no charge for the swap.
What a contrast with Japan, where prepaid SIMs and USIMs are prohibited by law.