Yes this is indeed possible.
Firstly is the wcf in a seperate application / project / solution?
If hosted inside the web app, this is very easy to accomplish as the site and service all get fed from the same place. If a separate application / service you will need to configure a separate website on your IIS box (assuming you are using HTTP based wcf).
Once you have set this up you can distinguish between the two sites using host headers. Host headers are used to recognize requests and re-direct them based on name to the same ip. IIS re-directs the request to the correct site based on the request header.
Host headers
http://technet.microsoft.com/en-us/library/cc753195(v=ws.10).aspx[
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WCF IIS
http://www.youtube.com/watch?v=mX8quq7MoeI[
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A Beginner's Tutorial on How to Host a WCF Service (IIS Hosting and Self Hosting)[
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