Some plans are beginning to offer disability insurance for 401K contributions, that is in the event of the disability of a plan participant, contributions are still made. According to one policy, monthly contributions are made from the time of the disability to the age of 65. Another policy holds an annuity in trust for the plan participant, with payout beginning at age 65.
Regarding "disability 401k insurance", your best option here is purchasing an individual plan of disability income insurance that will make your 401k contributions in the event you are sick/injured and unable to do so.
Several of the leading individual 401k insurance providers offer these policies, however they are fairly new and very few advisors are currently discussing these as part of a sound income protection plan.
So in terms of your questions "How frequently is 401k insurance offered"..... By employers very very rarely... By financial advisors rarely.... The good news is anyone who is approved for disability insurance and contributes to a 401k plan can obtain this type of coverage.
I hope this helps.
I believe that this is a question that could best be answered by your companies HR department since this is something that is offered by some companies and not all companies and it will vary from company to company.
If you get some more information on this and would like to discuss it some more you can always look me up and I'd be happy to talk to you about it.