I'm on a Linux box and I need to load/import/export files to/from a Z server running 9.1 My import/load/export tests fail with:
"SQL1325N The remote database environment does not support the command or one of the command options."

I have found indications that this might be a limitation of connecting to the Z and that this will never work. can anyone confirm this?
Server/Version = DB2 OS/390 9.1.5 "LINUX390X64"

Here is a sample command:
db2 load from testfile.dat of del insert into someschema.test_table

I've tried this from a Windows box and a Unix box with the same error. Any ideas?

I assume testfile.dat sits on your Linux client machine. If that's the case, you have to specify LOAD CLIENT FROM ...

Try import using IXF format. Please take a look here:
DB2 Database for Linux, UNIX, and Windows

An other option would be to load into a replica (temp) table on the Linux DB2 in step 1, then replicate that table into the z/OS DB2 table (with plain SQL).

I had already tried the "load client" option with the same error.

I'm trying to load text/dat/csv files downloaded from various sources. They are not in ixf format.