1.5 months is not shit (not to cut or to make your habit seem small)...
Seizures really dont come into play with opiate w/d, that mainly has to do with alcohol and benzo withdrawls. I would assume you mean really shaky feelings which I find benzos literally to be a lifesaver in detox. Any reputable medical detox worth its money will use benzo's in conjuction with other meds to help ease the 'kick'. I would strongly strongly say stay away from methadone, its a horrible drug that usually puts people in a worse situation than they are in to start with.
Here is a little help with Bupernorphine, I have had great luck with it, a 2 week detox on bupe would be pretty much painless for you.
http://suboxone.com/Suboxone/phys/pharmfaqs.htm
Another option which I probably would give the first try would be: Go see a doctor (psych/family/etc.) tell him what the deal is dont lie. Ask for medication that will help you thru a detox. Most common medicines scripted for withdrawls are as follows (at least in my experience):
Benzos - (Valium, Atavan, Klonapin, Xanax, Librium, Restoril) In that order
Clonadine (patches or pills) blood pressure regulator - helps
Phenagren - helps with stomache discomfort
Compazine - helps with stomache discomfort
Trazadone - helps with sleep
Seroquel - sleep
Ibeprophen (sp?) - aches and pains
I could type out a normal cycle that worked for me ask if you want to know.
So basically, stay away from methadone, try it cold turkey if that doesnt work or is to much pain see a doctor. If that doesnt work maybe try buprenorphine or maybe consider checking into a medical detox facility. Dont take my words for it though, look around there is plenty of information out there. As it is quite a common disease. Some people might tell you to take a weaker opiate to wean yourself off, i.e. codiene, hydrocodiene, etc. but I find it just prolongs the process.
best of luck... Summer is one of the 2nd busiest 'kick' seasons with the holidaze (Christmas) coming in a close second.
*edit*
Dont start worrying about how bad your detox will be a big majority of w/d is psychological.