If you look at the properties of any virtual directory you've created under Internet Information Server, you'll see "Application protection" which will have options for High, medium, and low. If it's High (not sure about medium) you'll be able to press the "Unload" button right next to it to stop it without affecting Internet Information Server or any other apps.
I've automated this in a project hook using this VFP code in the BeforeBuild method:

DirObj=GetObject("llS://LocalHost/W3SVC/1/Root/"+myVirtualDir)
DirObj.AppUnload

>When compiling our Web Service into a DLL, is there any other way than to IISRESET /RESTART in order to be able to clear it from memory and be able to compile a new version?
>
>When compiling into a DLL, once loaded by IIS, the Web Service remains in memory and VFP won't compile a new version as long as it remains in there.