To be able to calculate the numbers for the commutation of part of a life pension, doing so only from the far end of the award, you have to know when you are going to die. There aren't many people who can supply that sort of information. You may be able to get a partial commutation of the life pension, but it would have to involve a reduction in the amount of the payments you would receive while you get the life pension, rather than coming off the far end. The DEU can make those calculations for you. Because of the cost of living adjustments that apply to most life pensions, you probably don't want to be asking for a percentage of the life pension. You probably need to ask for a specific amount.
You may be able to commute from the far end of the permanent disability as you know how much is due and when. As Mr. Batchelder indicated, it's tough to know how much and when the end of the life pension is.