The private-equity allocation is the most difficult to access. Some of the investment offerings that trade as private equity actually have stakes in the business of running private-equity funds, not the funds themselves. The vehicles that really are the pools of capital can trade away from their NAVs. I wrote about MVC CaptialMVC at the beginning of the year. It has a well-diversified investment mix and has been steadier than many of the other names in the space.
Individual issues are probably a better way to go if you would just use Treasuries for domestic bond exposure, and the suggested 5% doesn't leave too much room for a lot of different domestic exposures. Individual Treasuries should do the trick, but some other suggestions are noted below.
Foreign bonds have only one ETF to choose: the SPDR Lehman International Treasury Bond ETFBWX. BWX yields a little above 4.13%, but adding in some Aberdeen Asia Pacific Income FundFAX, a closed-end fund, would enhance the yield. If you allocate 5% to BWX and 4% to FAX, that would increase the yield by 100 basis points over just holding BWX. This play would avoid any unreasonable single country bets.
With the real estate allocation, you could find any of a number of REIT ETFs, but an odd thing happened last summer during the start of the financial sector meltdown. Real estate investment trusts correlated very closely with financial stocks, and anyone with too much exposure to both was forced to endure a lot of angst. Lately I have started to research buying publicly traded farms -- yes, as in agricultural ventures -- as a proxy for real estate in a portfolio.
