Creating something like this in LAYOUT.XML should be no problem from Photoshop:
<instance type="Sprite">
<properties>
<initial-visibility>Visible</initial-visibility>
<initial-frame>0</initial-frame>
<effect>(none)</effect>
</properties>
<world>
<x>150</x>
<y>150</y>
<z>0</z>
<width>256</width>
<height>256</height>
<depth>0</depth>
<hotspotX>0.5</hotspotX>
<hotspotY>0.5</hotspotY>
<angle>0</angle>
<opacity>1</opacity>
</world>
</instance>
However PROJECT.caproj also has reference to the Sprites.
Can I leave out the <collision-poly> details (as these will be impossible to recreate in Photoshop), or will I mess up C2?