Need to hotwire 99pontiac montana - 1999 Pontiac Montana

the easy way is to buy an aftermarket radio harness adapter if available

Can't say for sure but most radio's have a permanant hot wire to retain memory. You might have jarred loose that wire or possibly dislodged the plug eliminating it's contact. Other possible could be the hotwire has an inline fuse that popped.

hotwire is the movies - buy a key and cylinder with out the [chip] security setup from ignition will have no start -- because if you could bypass or "hotwire" wouldnt need keys or security

Can You Hotwire car Like in the Movies Hollywood Secrets Revealed

Here's a link to your problem. How to Hotwire Car

If you try to use a blank key chip in a vehicle that is meant to use a key with a chip installed, the chances are excellent that your vehicle will not start. The computer chip in the key mates with a piece of program code in your car's computer system. When the two halves are there, your Pontiac will start easily, however, if you attempt to bypass the coded key, your van won't start. For most drivers, this is not an issue, unless an ignition key is lost. If you lose the key you will have to replace it with a matching one which will prove expensive. It can cost up to $85 or more to replace this type of key in some cars because the key has to be encoded to work with your van. Unless you know someone with a blank spare for the same vehicle who will give the key to you, as well as someone who can program the key, then you will have to pay the freight on a new key and encoding. If you would like further information on this and other automotive issues, please take a look at <a_href="www.safecar.info">www.safecar.info</a>.

computer needs that chip in key. this is to prevent theft

You won't be able to hotwire it due to the passlock antitheft system. Read about it in this link.
http://vatspasslockpasskeysecurityhelp.yolasite.com/

First you'll need to determine if the fuse and / or relay is good. If so, then check the seat switch by ' hotwiring ' ( running a positive wire from the battery to the positive side of the switch ) . if the hotwire worked, your switch is bad - if not then you may have a bad seat motor or corroded connection. You may need to remove the seat from the vehicle to further test connections and / or run your hotwire to the positive side of the motor, which may be difficult at best. I'd check the fuses first, then relay, the call your local shop since everything else can get complicated.
Good luck!