I think there's a small confusion in terms between a style and a theme. You are talking about defining custom styles for a widget in your application. A Theme is a collection of these styles applied globally to an Activity or Application. The custom styles you have created for a button and text view can be applied to a new custom theme so all buttons and text items share the same attributes.
I think what you are looking for is something more like this.
<style name="ApplicationTheme" parent="android:Theme.Holo">
<item name="buttonStyle">@style/MyButtonStyle</item>
<item name="textAppearance">@style/MyTextAppearance</item>
</style>
<style name="MyButtonStyle" parent="android:Widget.Button">
<item name="android:drawableLeft">@drawable/ic_launcher</item>
</style>
<style name="MyTextAppearance" parent="android:TextAppearance">
<item name="android:textColor">#ff0000</item>
</style>
Here, we have created two new styles (one for the button appearance and one for default text appearance), and then applied those as attributes in a new custom theme. You can now apply this theme in your manifest or in View constructors by referencing @style/ApplicationTheme
or R.style.ApplicationTheme