Can I do an impdp with a file on my local computer
Should be possible, provided the user that the DB service is running as can access the file share.

If the above is true, then you would have to create the directory object: 

create directory MYIMPORTDIR as '\\mycomp\mydir';


then run your impdp like:

impdp [username]/[pass] directory=MYIMPORTDIR dumpfile=expdat_1234.dat