You have the right idea, but it should be noted that you are using numbers from 2011, and your dividend rate is way off.
The key unknown variable at this point is the amount of foreign tax as a percentage of the dividend distribution. Last year's number was 6.5%, although I think the historical average is more like 7%. In 2010 it was 8.8%.
I believe this number will not be released until January.
Assuming you held exactly 1000 (Admiral) shares of Total International between September and now, then you would have been paid $746 in dividends. At 7%, that would be $52.22 in foreign taxes. (And your 1099 would report a total of $798.22 = $746 + $52.22 in dividends.)
So to hit $300 in foreign taxes under the 7% and constant number of shares assumption, you'd need 5744.925 shares of VTIAX. Using the price at today's close, that's $142,876.28, give or take a few thousand.