Ehh, just looked at the FrameXML for a second and cooked this XML up. No clue if it will actually work.
Code:
<Ui xmlns="http://www.blizzard.com/wow/ui/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.blizzard.com/wow/ui/
..\FrameXML\UI.xsd">
<Frame name="SomeFrameName">
<Size>
<AbsDimension x="50" y="50"/>
</Size>
<Layers>
<Layer level="BACKGROUND">
<Texture file="yourfilepathhere">
<Anchors>
<Anchor point="TOPLEFT">
<Offset>
<AbsDimension x="0" y="0"/>
</Offset>
</Anchor>
<Anchor point="BOTTOMRIGHT">
<Offset>
<AbsDimension x="0" y="0"/>
</Offset>
</Anchor>
</Anchors>
<Scripts>
<OnLoad>
self:GetParent().tex = self
</OnLoad>
</Scripts>
</Texture>
<FontString inherits="GameFontNormal">
<Anchors>
<Anchor point="CENTER">
<Offset>
<AbsDimension x="0" y="0"/>
</Offset>
</Anchor>
</Anchors>
<Scripts>
<OnLoad>
self:GetParent().text = self
</OnLoad>
</Scripts>
</FontString>
</Layer>
</Layers>
<Anchors>
<Anchor relativeTo="UIParent" point="CENTER">
<Offset>
<AbsDimension x="0" y="0"/>
</Offset>
</Anchor>
</Anchors>
</Frame>
</Ui>
Probably some unneeded stuff there (offsets in particular), but no clue which tags are optional.
Now if you might excuse me for a moment, because I feel like I'm going to throw up at any moment.
PS: If you want to keep them separate, make two Lua files. Just do it.