You original routing and taxes are shown on your paper ticket - even though you have used some coupons, a "carbon copy" remains in the ticket booklet (unless you have thrown the first booklet out once finished with it and only retained the booklets with the unused coupons).
Presumably you are re-issuing because you want to change your routing? If there is already a PNR for some or all of the segments you need change, change the reservation on that PNR so that it is ready for when re-issue happens - speeds it up.
No reason why you can't reissue in HKG - you will most likely have to go to the ticketing desk (although Wing/Pier may assist with this). It may be advisable to call ahead and warn them that you will be wanting to do this. Others who have actually done this in HKG can elaborate.....