I have never grounded my Honda 2KW generator. Not sure if you should, I just haven't.
When using my generator attached to the TT 30A Shore cable w/ 30A-20A dogbone, my SurgeGuard Electrical Managemet System (EMS) thows an "open ground" fault and prevents current from entering the TT. This is common when using a generator and EMS, because the Generator isn't grounded. To me this probably indicates you should ground the generator, but I and many other don't.
As for getting the EMS to allow the current to flow with an ungrounded generator, you need to either bypass the EMS or better yet create an adapter that ties the ground and neutral lines together -- this statisfies the EMS.
If you or others want more information on creating the adapter there are numerous threads you can read on the various forums. They are very easy and cheap to make...but be sure you are confident in the power you generator is outputting first. Doubt I would use this on a low cost contractor grade generator that doesn't output a pure sine wave