Я предлагаю использовать отражение:
private void setIndecator(TabHost.TabSpec tabSpec, String label) {
LayoutInflater vi = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
LinearLayout tabView = (LinearLayout) vi.inflate(R.layout.tab_view, null);
((TextView)tabView.findViewById(R.id.tabCaption)).setText(label);
try {
Method m = tabSpec.getClass().getMethod("setIndicator", View.class);
m.invoke(tabSpec, tabView);
} catch (Exception e) {
//in case if platform 1.5 or via other problems indicator cannot be set as view
//we have to set as just simple label.
tabSpec.setIndicator(label, getResources().getDrawable(R.layout.tab_selector));
}
}