Hi,
You cannot have a salary structure for expats as they will be here for a fixed term. Break the compensation into two parts: one, the cash, and the other, benefits. By cash, I mean the salary which will be paid every month by cheque/bank transfer, etc. The second part could include company-paid accommodation, company-paid car + driver, company-paid club membership, etc.
In my company, we have an expat from our parent company in the UK on deputation for 2 years in our India office. We are paying him a fixed amount every month, subject to applicable local taxes and the above benefits. Before deducting taxes on his monthly compensation, check with the expat on his tax implications in his home country and consult your finance department on the possibility of dual taxes (where the expat might end up paying taxes in both India and his/her home country).
Hope the above information helps.