It's pretty simple. All you need to do is say that your module isa HTML::Parser:

package MyParser;

use HTML::Parser;
@MyParser::ISA = qw( HTML::Parser );

sub text {
    # do what you will here
}
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Methods called on instances of your class that aren't found in your package will be found in parent classes (Perl examines the contents of your @ISA). If you provide your own, it won't go loooking up the inheritance chain.