I'm coming at this from a different direction, just to see if I can get this to work.
I've created a seperate rewrite map called samwin.config which looks like this:
<rewrite>
<rewriteMaps>
<rewriteMap name="samwin">
<add key="mens-clothing/coats" value="ProductsInCounter.cfm?subcat=5462&ShopRef=73&cat=574" />
<add key="mens-clothing/coats/raincoat-black" value="ProductDetailInfoWithOptions.cfm?ID=SW-BVG06&ShopRef=73&Prime=Yes&shopListRec=41251" />
</rewriteMap>
</rewriteMaps>
</rewrite>
I call this from web.config as follows:
<rewrite>
<rewriteMaps configSource="samwin.config" />
<rules>
<rule name="MainRewrite" stopProcessing="true">
<match url=".*" />
<action type="Rewrite" url="{arseface.config:{R:1}}" />
</rule>
</rules>
</rewrite>
However, I get a 500.50 URL Rewrite Error. The error code is 0x8007000d, and the Config Error states "Specified configSource cannot be parsed", referring to this line: <rewriteMaps configSource="samwin.config" />