there were a few things i did that i thought made it work after getting the same "The parameter is incorrect." Error.
1) restarted machine and did it again. it worked the first time.
2) made sure i was in c:\ and put the command again after restarting didn't work
i couldn't explain why but i think that maybe both times, there was something else wrong. because the third time this happened to me,
3) i went through the thumbprint of my CA (not the issued server cert) and copied it again from the MMC and it worked.
after this happened, i deleted it again (netsh http delete sslcert ipport=0.0.0.0:) and repeated the process using the thumbprint of the server certificate. The darned thing worked again.
I dunno, just try going through the same thing I did. maybe one of these would work. In the end, i suspect that I entered a bogus space or character in the certhash.