First try : 

root@pscdweb1:/.cpan/build/Text-Iconv-1.7-ziellw# /opt/perl-5.10.0/bin/perl Makefile.PL 
Checking for iconv ... fail
Failed to find iconv, please check your settings and re-run as:
/opt/perl-5.10.0/bin/perl Makefile.PL LIBS='-L/path/to/lib' INC='-I/path/to/include'

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Second try: (added LIBS and INC arguments to Makefile.PL)

root@pscdweb1:/.cpan/build/Text-Iconv-1.7-ziellw# /opt/perl-5.10.0/bin/perl Makefile.PL LIBS='-L/usr/lib' INC='-I/usr/include'
Your settings:
  LIBS: -L/usr/lib
  INC:  -I/usr/include
Checking for iconv ... fail
Failed to find iconv, please check your settings and re-run as:
/opt/perl-5.10.0/bin/perl Makefile.PL LIBS='-L/path/to/lib' INC='-I/path/to/include'

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