Is it possible to take a mutual fund and reinvest in it one's one portfolio of stock purchases without incurring the taxes of selling the mutual?

From my experience, no. It's like buying an orange at the store and trying to change it into an apple. Mutual funds and stocks are completely different entities of the market and thus needs to be sold to buy other products.

However, if you DO find a way to do that, please, feel free to share... as my mutual funds are tanking.

Only if the trading is done within a 401k or IRA. Otherwise, you'll have to realize the capital gain. But, given the fact that Obama has indicated that he plans to increase the cap gains rate back to 20 percent, now isn't a bad time to take some gains.