If they start you on another med right away you may not go thru any withdrawl. Depends on you and your dr. You need to let your dr know what a hard time you have without it. Hopefully the next med they put you on will help you.
If you need full information on anti-depressents and mood stabilizers the following sites would be of help:
http://www.medhelp.org/health_pages/Mental%20Health/Useful-Bipolar--Depression-Webisites/show/523?cid=105
Anti-depressents can worsen mania in people with bipolar but some mood stabilizers have more of an anti-depressent effect than others. Speak to your psychiatrist about it.
Unfortunately my experience with paxil/seroxat/paroxetine was really bad. It took quite a while for withdrawal. The reason i tried it, is that i read that it goes well with lamictal. my pdoc was a fool i suppose, i tried many pdocs at the time, and since i tried lexapro/escitalopram/cipralex and drove me manic after 2 months I switched to paxil to realise that it's stronger. they say the strongest is effexor. I suppose all SSRI aren't suitable for BP. You are right go very slowly with it even if it takes a long time. However while I was withdrawing from it i took stablon an SSRE it was tough but in order not to crash quickly so i landed smoothly.
I really can't tell you more, except very slow withdrawal. All i can say is Good Luck. it isn't your fault, the brochure of seroxat says it needs long time to wean off. I am sure your pdocs know some tricks to reduce withdrawal symptoms, perhaps some antipsychotics which contain antidepressant properties like seroquel.