What I tried to say it's that the L305 models of Toshiba (in my opinion) can run the Leopard without problems. However, if the processor or some hardware differs, it's obvious that you'll have to get the right Kext files :P

Concerning the topic of the time/date I partially solved my problem with the most simplest I could do: synchronize the time/date with a server. However, this fails if I'm not connected to Internet.

I'm testing the 3G support pal, I found that there is an application which manages the Huawei modem (in my case) to connect to Internet. Even though the device is correctly detected and I can see that the network is detected too, I can't connect. I'm trying to configure the Network Settings to see if I get it working. If I get any results I'll post them here.