Pick a piece or pieces and start contributing to the effort... your suggestions will then carry a lot more weight
You do not seem to have found or tried my OpenACS4 RPMs yet? Searching for the two words "openacs4 and "rpm" will find the relevant posts in these forums. It is early days for the packaging process, because the codebase is still alpha. But by all means try my RPMs and provide feedback on how well they do or don't work for you. Read this to get started.
Once you have OpenACS4 up and running, if you have the skills and experience to design a good default "look" for OpenACS4, and/or make that look "themable" ... go for it -- put the work on display on your own demo OpenACS4 web site, and post a message here with a URL so we can all look at your work and provide you with feedback... that could be a good contribution for you to make.