used to be possible until the lastest security chip became common in vodafone`s lineup and until that one has been hacked, the supply is really really low. you are prob better off looking for someone who is willing to sell off their used imported modified sets. Japanese phones are really cool but then the hacks are known to be unstable or unable to get the full potential out of the phones, not to mention limited language support as well.
one more point to note is that the japanese companies jacked up their penalties pretty high for early contract termination so, the new phones will cost a lot more now.
vodafone has some cool gsm sets, the ones that they loan out at the airport counters are crap. the vodafone counters have various sets that are useable on GSM networks but restricted only to their own gsm sim cards by a security chip. the older models with the older models about 2 years back, could be hacked and then replaced with a modified OS to work in taiwan, HK, china and SG. but those are not cheap. about nearly a 1k.