I presume that you mean to take the result of the Split Segmentation and map it to an evar, yes? If so that should be easy enough - the output of the Split Segmentation is set to a 1st-party cookie and is set before SC runs. So you can just map the cookie to whichever evar necessary.
For example, if your cookie is called "my_split" it should be stored in the utag_main namespace. So declare a cookie in the Data Layer tab with the name "utag_main_my_split" and give a type of "Cookie Value". Then in the Split Segmentation extension set the Destination Cookie to "utag_main_my_split (cp). Then go to the Tags tab and map "utag_main_my_splot (cp)" to the appropriate evar.