You're correct textures can't have a Scripts section and you'll want a button that contains the texture. I assume you have the texture in the Layers section? Here's a "before" and "after" to move the texture to a button. It can be done in different ways:
Before:
Code:
<Frame name="MyModFrame" parent="UIParent">
<Size>
<AbsDimension x="200" y="200"/>
</Size>
<Anchors>
<Anchor point="CENTER"/>
</Anchors>
<Layers>
<Layer level="BACKGROUND">
<Texture name="MyModTexture" file="Interface\Icons\INV_Misc_Coin_01">
<Size>
<AbsDimension x="32" y="32"/>
</Size>
<Anchors>
<Anchor point="CENTER"/>
</Anchors>
</Texture>
</Layer>
</Layers>
</Frame>
After:
Code:
<Frame name="MyModFrame" parent="UIParent">
<Size>
<AbsDimension x="200" y="200"/>
</Size>
<Anchors>
<Anchor point="CENTER"/>
</Anchors>
<Frames>
<Button name="MyModButton">
<Size>
<AbsDimension x="32" y="32"/>
</Size>
<Anchors>
<Anchor point="CENTER"/>
</Anchors>
<Layers>
<Layer level="BACKGROUND">
<Texture name="MyModTexture" file="Interface\Icons\INV_Misc_Coin_01">
<Size>
<AbsDimension x="32" y="32"/>
</Size>
</Texture>
</Layer>
</Layers>
<Scripts>
<OnEnter>
GameTooltip:SetOwner(this,"ANCHOR_RIGHT")
GameTooltip:AddLine("You entered MyModButton, which only contains MyModTexture")
GameTooltip:Show()
</OnEnter>
<OnLeave>
GameTooltip:Hide()
</OnLeave>
</Scripts>
</Button>
</Frames>
</Frame>
You'll note <Size> is defined both for the Button and the Texture. The OnEnter event is actually for the button itself, so we need the button to cover the 32x32 to receive the OnEnter. The texture can be 64x64 on disk, but I don't believe it limits itself to the size of its parent. (Could be wrong on this). So a 32x32 size is defined for the texture too. Alternately, instead of a <Size> within the Texture, you can set two anchors:
Code:
<Texture name="MyModTexture" file="Interface\Icons\INV_Misc_Coin_01">
<Anchors>
<Anchor point="TOPLEFT" relativeTo="MyModButton" relativePoint="TOPLEFT"/>
<Anchor point="BOTTOMRIGHT" relativeTo="MyModButton" relativePoint="BOTTOMRIGHT"/>
</Anchors>
</Texture>
This will stretch the texture to cover the entire Button. So you only have to worry about the Button's size.
Every last tag isn't needed and some shortcuts can be made (ie, relativeTo can be dropped I'm pretty sure) if you run across other examples.