You don't really want to splice them. I'm assuming this is for cable modem/TV service, right? You put an S-connector on the ends and use a barrel to connect the two cables.
You use a tool like this:
http://www.techtoolsupply.com/index....MMP=1012674616
Here's the "barrel" I speak of:
http://www.techtoolsupply.com/index....ROD&ProdID=861
Note that these are just representative samples that I found, there are lots of places to get this stuff. I recommend the compression connectors, they work really well and are easy to install.