Since you're already using the JS implementation of iMacros, wouldn't it be easier just to manipulate that information with JS?
var extractString = iimGetLastExtract();
var firstNumber = extractString.substring(0,1);
var secondNumber = extractString.substring(2,2);
That's assuming that you'll always be looking for the first number and the second pair of numbers. You can also use regular expressions with the JavaScript String match() method, but that'll dump an array of values.