There would certainly be chances to do what you are thinking of; probably your best bet would be to start trawling ads in the SCMP classifieds. It will be more likely to get a position in a primary than a secondary school (although there might be the occasional desperate band 3 high school, if you REALLY want to jump in the deep end...). Depending on the number of other applicants, you would also have a fighting chance to get into the EdB PNET scheme - if you do, I understand you need to undertake to get additional qualifications (PGDE) in your first couple of years' employment.
As far as I'm aware, international schools don't normally employ special ESL teachers; the assumption is that students are already comfortable learning in English. To get your foot in the door there, you will need both formal qualifications and some years classroom experience using the curriculum that your "target" school follows. A possible exception would be if your current degree is in a subject area where a teacher is needed in a secondary department.
This is a rough guess, as I'm out of the loop pretty much, but at the bottom rung as a non-EdB PNET, say, 25K (??). PGDE / getting into the EdB scheme bumps this up 10K +.