Is a Deferred Compensation retirement payment elgible for a Solo 401K contribution?

I received a deferred compensation payment 1 month after I retired from my employer of 30 years.  This will appear as W2 income, likely in box 11 - nonqualified plans. Since I am no longer employed at the company I am not eligible for contributions to their 401k plan.  Can I make a contribution to a solo 401K plan using this income?