I’m afraid I can’t help you get Cubase LE1 running on a Mac, but the file format of the old sessions is still readable by the latest Cubase versions.
As an alternative, if you had registered your Cubase LE license under your account on MySteinberg, you should request a transfer of the Cubase LE license to the latest Steinberg Licensing system. This would then enable you to download the latest version of Cubase LE and run it on current versions of Mac and Windows, and be able to open your old sessions.
The only problem is getting someone in Steinberg to do that transfer for you. You should first try logging a ticket on “My Steinberg”. You should also check the following topic and add a request for Matthias, who has assisted others.