In reviewing his code, it appears that the largest source of issue was that apparently, in my code, you cannot index the "rules" object using a string.

Thus, the following code is more appropriate (for anyone who might be watching/stumble upon this code):
Code:
function swapStyle()
	{
		var sCurrent;
		var iIndex;
		for (iIndex = 0 ; iIndex < document.styleSheets[0].rules.length ; iIndex++)
		{
			if(document.styleSheets[0].rules[iIndex].selectorText == ".hideable") break;
		}
		if(iIndex == document.styleSheets[0].rules.length)
		{
			alert('not found');
			return;
		}
		sCurrent = document.styleSheets[0].rules[iIndex].style.display;
		if(sCurrent == "none")
		{
			document.styleSheets[0].rules[iIndex].style.display="";
		}
		else
		{
			document.styleSheets[0].rules[iIndex].style.display="none";
		}
	}