You are correct in your assumption here. The global IP address on layer 2 code will not translate to an IP address on layer 3 code. The only way I could see you doing this remotely would be to do a lab and get the proper configuration on layer 3 code using the same hardware. Once you have that, you could save it off via 'copy start tftp' command and then load it to the remote switch via 'copy tftp start' command. Once copied, you can issue a 'show config' to confirm the new startup configuration is copied. You can then reload being sure *not* to issue 'wr mem'.
This is still obviously risky as you would not have certainty that it would be reachable post-reload.
Ben Beck, RCNA, RCNI, Principal Technical Support Engineer