------html-------
<INPUT name=text1>
<INPUT name=text2>
<INPUT name=text3>
<INPUT name=text4>
<INPUT type=submit value="ここ押せ" name=hoge>
-----------------

-------cgi--------
#!/usr/bin/perl
require 'cgi-lib.pl';
require 'jcode.pl';

&ReadParse(*in);
$txt1 = "$in{'text1'}";
$txt2 = "$in{'text2'}";
$txt3 = "$in{'text3'}";
$txt4 = "$in{'text4'}";
&jcode'convert(*txt1,'sjis');
&jcode'convert(*txt2,'sjis');
&jcode'convert(*txt4,'sjis');

処理
---------
こんなもんだろ。