The actual data in the .dmp file is not HCC-compressed; it's just the table definition that has "COMPRESS FOR ..." in it. So you can precreate the table without HCC compression, and then just run an impdp with TABLE_EXISTS_ACTION set.
To Export form Exadata (DB 11g R2) and Import into Older versions of Oracle (Ex. 10g)
You have to use exp utility which is version 10g and imp by utility 10g
Ex. use oracle 10 client to connect to Exadata and run exp cmd then imp.