Capital Gains from mutual funds

[Matti Picus]

Tax law in Israel is ever changing, and I would like to develop a report 
that will allow "what if" calculations of mutual funds. Here are the 
problems:
1. The fund transactions are made in dollars, but the calculations must 
be done in shekels (I need to look up the exchange rate and multiply)
2. Each purchase must be aligned with a sale, in a first-in-first-out 
fashion. That is, I buy five shares in 2002, fifteen more in 2003, and 
sell 10 in 2004 and ten in 2005. The capital gains in 2004 is against 
the shares purchased in 2002 and 1/3 of the 2003 shares, the 2005 shares 
are calculated against the 2005 ones.
3. I also need to adjust the values for inflation, using a well known 
consumer price index.
4. Of course I need to be able to fix the rate of taxation.

How can I start to implement this? Any hints?