update cell text without refreshing

Is there a way to update the text of a cell (specifically a footer cell) after the grid has rendered but without having to call an obj.refresh? I'm doing an ajax call to load totals since some of my record sets are very large and need a few seconds to sum. I've tried using

obj.setFooterText(myTotal, columnNum);

but that only displays the new value after calling a refresh, and I want it to appear right away. Thoughts?

It is possible refreshing just the single footer cell -

obj.setFooterText("some text", 1);
obj.getFooterTemplate(1).refresh();

or, if you are using extended grid (which allows multiple footer rows) -

obj.setFooterText("some text", 1, 0);
obj.getFooterTemplate(1, 0).refresh();