As far as I know you cannot, as tye put it on the chatterbox:

data structure dereferencing is interpretted inside of double quotes, but method calls and code dereferencing aren't

This is more easily seen if you use the OO form of CGI.pm:

use CGI;
$cgi = CGI->new;
print "$cgi->textfield(-name=>'cgifield',-size=>'20')";
print qq/$cgi->textfield(-name=>'cgifield',-size=>'20')/;
print <<EOL;
$cgi->textfield(-name=>'cgifield',-size=>'20')
EOL

#all print CGI=HASH(0x...)
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