Essentially because there ceased to be an official IPSec client when Secure Computing stopped selling the re-badged SafeNet VPN client, I think that Shrewsoft has become the accepted alternative.
If you run a search on this forum for Shrewsoft you will find a number of articless, at least one of which I recall containing a link to an article written by one of the forum contributors explaining how to configure it.
Dear kdesnayer, please take a little time to look for inside this community and you shall find it, take a look to user dgold reply. He/she attached a document about how to configure ShewSoft client with Sidewinder V7. I think it could help you.
Better still, I've just noticed that if you look at the right-hand side of this page, you will see a section called "More Like This". The "Approved VPN Clients" link is quite likely to be the one you are looking for.
Even though you have stated that you are running version 8, there appears to be little difference in the IPSec implementation and the Admin Console configuration screens between this version and version 7. So any articles relating to v7 should be equally applicable in your case.
We have a few knowledgebase articles about VPN clients and the Sidewinder:
KB64156 - Support for VPN clients
KB64323 - How to create a VPN using the GreenBow client
KB67215 - How to create a VPN using the ShrewSoft client
KB64219 - How to create a VPN using the SoftRemote client