|This modem you speak of, is it a combination unit? Which is to say, it's a combination modem/wireless router.|
If it's just a modem, it's not wireless capable and you can't connect an AP to it wirelessly.
If it's a combo device, or you have a modem and separate wireless SOHO router, you would bridge it to your existing WLAN to connect via wireless.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.