Without understanding the exact situation (for instance whether you are referring to your manager or simply other people in your team) - some tips:
1) Reposition the proposition from "delegating" to "collaboration". You want to foster the attitude of co-creation, collaboration and team work. Therefore, share the entire Big Vision view with your target team. As in attracting sponsors and investors, prepare some type of proposal that includes what you trying to accomplish or the problem you are trying to solve. This will attract people that share the same vision and goal. In your pitch or proposal, include required skill level, level of effort, estimated time period and reciprocation for teams time and effort. In other words, be clear on how this will benefit them (either in regards to their career advancement, monetary reward, etc.)
2) Ask for advice on the areas that you are interested in getting help. Be open about your current skills level and the skill level that you feel is required to be successful. Ask for advice on who they feel have that skill level and interest in helping. At that point, they may either offer their assistance OR point to someone better. Either case, it's a Win/Win.
3) Acknowledge and appreciate their skill set. Make sure you explicitly state your admiration for what they can bring to the team and that is why you are coming to them for advice. And make sure you stay involved. Do what you say you are going to do in regards to this project.
When 'delegating up - People are more apt to assist if they see it as a Win/Win situation. But if they see it as a "delegating" or 'washing your hands of it' - you will not get the results you were hoping for.
Hope this helps a little. If you had more detail to your specific issue - I think I could have helped a little more.
Having been in senior management and a CEO for many years, I have found that delegating is not only a skill but also an art. You question is very interesting as I assume that in most situations you would be delegating to people more skilled or more knowledgeable about the task or project than you are. A good manager knows their limitations and their role which is to manage rather than do. Therefore the rules on good delegation techniques still apply:
1. Identify the right person or team with the right skills and experience to do the work. It sounds as if you have done this. Write down the reasons that you feel that they will be better placed to get the best results and portray this to the person up front.
2. Be clear on the level of delegation that you are giving to them. There are 9 levels (if you would like to know these, please let me know). This includes a detailed briefing to outline the tasks/outcomes.
3. Negotiate the timeframe, reporting and results. Don't tell, ask - then double the time they estimate. Most of us underestimate the time anything will take. By providing the person with extra time they will feel much more positive about the tasks and be confident on delivering the outcome.
Negotiating the timeframe, reporting and results is the most important step. Never dictate this as you really want a good outcome and this will only be achieved if they are part of this decision.
Please call me if you would like some more practical help.