Instrumented indentation testing (IIT) is a very useful technology for the mechanical characterization of materials. However, existing IIT techniques, which are based on the Hertz model and were developed for hard materials with negligible surface adhesion such as metals and ceramics, are difficult to directly apply to compliant materials such as elastomeric polymers which have viscoelastic hysteresis due to infinitesimal surface/interfacial adhesion. Here we employed some modified model to evaluate the work of adhesion in elastomeric polymer from our previous work, and reinforced our theory and algorithm through empirical approaches so as to consider the time-dependency of viscoelastic material as testing parameter. To do these all, we combined analytic JKR theory and conventional IIT technology to analyze the physical meaning of the theory and then verified our ideas experimentally with elastomeric polymer, PDMS (poly(dimethyl-siloxane)), of various compositions. Our algorithm was developed and verified on a microinstrumented indentation basis and extended even into the nanoinstrumented testing for the micro/nano-scaled applications.