OS X & Checkpoint VPN

It depends on how their VPN is setup. You need to know

What protocol is used (likely IPSec)
Is it UDP encapsulated and if so what port do they use?
What is the server's ip address
What the authentication mechanism is

I would imagine its using IPSec possibly with UDP encalsulation to make it easier to go across home routers and such. So you might need to know the port that they are forcing the encapsulation into. There should be a file called userc.c which contains the configuration information for a Checkpoint VPN client (likely a product called Securemote). If UDP encapsulation is used there will be a line like "Force UDP Encapsulation" which should list a port number.

For authentication it should be fairly easy if you are using a name and password. You might need a digitial certificate depending on how they configure it.

Please keep in mind while I know quite a bit about VPNs (I manage the VPN service for a large global company) I do not know much about the OS X VPN client and what it is capable of (I'm still waiting on G5 updates before I buy a mac). So certain tweaks done on Checkpoint may prevent the generic VPN OSX client from working.

Hope this helps
-jim