running a command that requires two parameters on a file

[Haines Brown]

I am in the habit of bringing up ! in order to run a command such as
xpdf on a selected file.

The problem comes when I want to run the command wkhtmltopdf, for it
calls for two parameters. That is, emacs won't let me do: ! wkhtmltopdf
input.html output.pdf.

Is there a way I can do this withou raising a terminal to make the
conversion with it?

Haines Brown