My original answer doesn't work, based on what I'm reading in perl5200delta.pod:

We now build binaries for miniperl and generate_uudmap to be used on the host,
rather than running every miniperl call on the target; this means that, short
of 'make test', we no longer need access to the target system once Configure is
done.  You can provide already-built binaries through the C<hostperl> and
C<hostgenerate> options to Configure.

So it sounds like if you're doing the cross-compilation correctly, perl shouldn't be trying to run generate_uudmap locally... Strange! You may want to post a perlbug about this if you can't resolve it, sounds like something strange is going on.

Make sure you reread the Cross-compilation section of "INSTALL" first, though.

I've never tried this, but this may work.

In a separate tree, build ugenerate_uudmap *natively* for your platform.

Then copy the binary into your cross-compile tree, and make shouldn't try to rebuild it but would just run it (unless the makefile builds and runs it in the same rule).

Good luck!

PS: You may have to rinse/repeat for other helper programs, I'm not sure