Are you trying to use something like this?
PLASTIC CHOCOLATE - Australian measures
500g dark chocolate
8 1/2 tb liquid glucose
5 ts water
Mix liquid glucose and water until completely combined.
Melt Chocolate either in double boiler of microwave.
Mix glucose mixture into chocolate until dough forms,
Wrap chocolate dough in plastic. Stand in a container on kitchen bench 4-8 hours [over night is fine].
Cut chocolate dough into 5 cm cubes then zap in microwave to soften before use.
Australian Liquid Glucose is thicker than American Corn Syrup. The addition of a feww teaspoons of water thins it sufficiently to use to make a pliable mixture.
There are a selection of Chocolate Rolled Fondant recipes available. Instead of flavouring a commercial brand, try this recipe:
Chocolate Rolled Fondant - Australian measures
1 tb gelatine in
1/3 c water
1 tb glycerine
Â½ c liquid glucose
2 tb shortening [not butter]
1 ts vanilla[optional]
Â½ c ordinary cocoa powder
1 kg icing sugar mixture [pure icing sugar is fine as longer as there are NO lumps]
Sprinkle gelatine over water. Sit the bowl in a pan of hot water for 5 minutes. Stir until dissolved. Add glucose, glycerine and shortening then stir until melted. Set aside.
Sift sugar and cocoa powder into a large bowl. Retain approx. 1 cup to use when kneading dough. Make a well in the centre and pour in the gelatine mix.
Stir with a large metal spoon, then knead by hand. As it comes together as a dough, add some of the retained sugar if required, if it feels sticky.
Dust surface of the bench with sugar before dumping out the dough. Knead until smooth. Add more sugar if sticking.
The sugar should be absorbed into the chocolate fondant and not sit on the surface discolouring the brown surface - a greased surface, should be used for the final roll-out before covering the cake.