We have just finished optimizing our site, and have two other URLs pointing to it as well. I wanted to have 301 redirects from the other URLs to the new one, but our ISP provider doesn't/won't do them. They said a meta refresh is fine. I don't want to get penalized for spamming and want the 301s used.

I was wondering about just putting up splash pages at the unused URLs w/ a click here to go to new site, hoping that gradually over the next few months, these URLs would disappear from the SERPs. Is this adviseable? Any suggestions as to what to do?