wilderness - 9:44 am on Feb 16, 2010 (gmt 0)

There's really not a simple answer to this.
Either you spend lots of time achieving the regional vieweing
OR
You pay somebody for the same goal (not foolproof and errors will occur).

Just using "white listing" and allowing the six specific country IP's you've specified would make your htaccess fairly large (in the thousands of lines), however a properly structured htacess may handle this many lines easily, absent any noticeable loss in access speed.
Just as long as the htaccess lines are NOT CPU/Server intensive.

There are multiple requirements that work unison:
1) Deny major SE's that offer bots strictly focused upon the regions you DO NOT desire.
2) DENY country refers
3) Deny translators
4) begin your IP denys with specific and complete Class A's.
5) make adjustments in your Class A's to allow access for exceptions.

Here's are some old Webmaster World threads in which I've saved links:

IP's Deny-Non US [webmasterworld.com]
Banning NON NA IP's [webmasterworld.com]
Blocking Several Countries [webmasterworld.com]
Block Country [webmasterworld.com]

The above are just examples of primary beginnings and ALL require a more comprehensive effort.

It should be note that most people find the concept of grasping and editing Rewrite lines of IP ranges quite mind-boggling. WHERE even a solitary syntax error will result in taking your server down with a 500 error.

Some syntax errors don't result in a 500 error for months and then one day you make a simple adjustment (correctly) and a 500 takes your server down.
If your htaccess is few lines, this 500-server-down does not present any real issues, however when your htaccess is thousands of lines, review could take days and result in distorted vision and migraine headaches.

In the end, each webmaster must determine what is beneficial or detrimental to goals of their individual site (s).