They sell freezer jam fruit pectin at my grocery store and I just followed the recipe on the back. I made rasp and bosenberry jam, but not blueberry. I did reduce the sugar it suggested, blues are so sweet I'd definitly cut back on the sugar. The freezer jam FP is really easy, you just crush the fruit and stir in the pectin and sugar. Mix for 3 mins and ladle it into tupperwares, let it sit for 30 mins and it's done.
If that doesn't suit your fancy, here is something Raine posted for me a couple months ago...
Making Freezer Jam
Raspberries, strawberries and blackberries work well in uncooked freezer jam recipes. You must store uncooked jams in the refrigerator or freezer. You can hold them for several weeks in a refrigerator and up to a year in the freezer. If you keep them at room temperature they will mold or ferment in a short time. Once you open the container, keep refrigerated and use the jam within a few days.
Sort and wash fully ripe fruit. Drain. Remove caps and stems from berries and crush. If you have fruit frozen, the preliminary steps for preparation have already been done. The label you put on the container of fruit should state how much fruit and sugar you added to the fresh fruit before freezing. Subtract the sugar added from that called for in the freezer jam recipe.
The basic recipe for uncooked jam is three cups crushed berries, about one and 1/2 quarts of berries, five cups sugar, one package powdered pectin and one cup cold water.
To Make the Jam: Measure three cups of prepared fruit into a large mixing bowl. Add the sugar, mix well, and let stand for 20 minutes. Stir occasionally.
Dissolve powdered pectin in one cup cold water in a saucepan and bring to a boil and boil for one minute. Add pectin solution to the fruit and sugar mixture. Stir vigorously for two minutes.
Pour the jam into clean freezer containers or canning jars, leaving one-half inch headspace. Cover the containers and let stand for 24 hours, or until the jam has set and become firm. This quantity makes about seven half-pint jars or freezer containers.
When jam comes out of the freezer, thaw overnight in the refrigerator. If the jam is too firm, you can soften it by stirring. If it tends to separate, stirring will blend it again. If freezer jam is too soft bring the jam to a boil in a saucepan on top of the range for one minute and it will thicken as it cools.