Looking around I found this solution.

I downloaded a new ASIO driver from http://www.asio4all.com/. It's free.
I set it as Audio driver inside the program.

Then I created a ReBirth Input Machine inside Reason and the signal from my audio card was right away available for any audio module (vocoder, reverb, etc)

From the RB Input Module audio out you can route the sound wherever you want.

It works!

sorry I forgot one thing.
during the ASIO driver installation, choose the option ReWuschel
bye

Good idea! I never really thought of this because I don't use vocals up until now, but well done, I'm sure this can help a lot of people

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so I can vocode live with this!!!!!??????????????????????? OMG PLEASE SAY YES!!! then ill have to get rebirth i guess though haha o well

yes, you can!
moreover, if you have a soundcard with stereo input you can use one channel for the vocoder mic and the other for any other external sound source (another mic, a bass, a guitar....)
it's nice
bye

can you record a guitar into reason or do you HAVE to use another program?

The best way to do it is with Rewire and a software that supports it like Nuendo,Cubase,Audition,Ableton, etc.) . If you want to be fast,simple and cheap , download Reaper and on their site there is a good tutorial how to start a Rewire Session.