[ic] Authorize.net works via [charge], not via &charge

[Grant]

I use Authorize.net within interchange via [charge] in a sort of
"virtual terminal" I set up in ITL.  I'd like to switch over to having
the charge take place automatically upon placement of an order, at
this point without giving feedback to the user about the result of the
charge.  I added these to catalog.cfg:

Variable MV_PAYMENT_ID mYiD
Variable MV_PAYMENT_SECRET mYsEcReT
Variable MV_PAYMENT_MODE sale

and:

&charge=authorizenet

to the mv_form_profile on the checkout page right under:

&credit_card=standard visa mc discover amex

When I submit an order like this I get the &credit_card error (if that
makes sense).  Am I leaving something out?

I must admit I don't have a proper order route set up, and instead
have an mv_form_profile on the checkout page and then a bunch of
processing inside [tmp hide][/tmp] on the order receipt page.  I know
that's disgusting.  It's left over from when I couldn't get order
routes to work years ago.

Can I continue like this for now and get authorizenet working, or do I
have to set up a proper order route?

- Grant