I assume that you have this circuit in LineSim. If not, export from BoadSim to LineSim. Simply add an IC buffer symbol connected to the point that you want to observe. Assign a model to that IC buffer that has no load and is just an input. Look in the Libs folder in the HyperLynx installation for a file named probes.mod. This file contains multiple models with varying quantities of capacitance in them. At least one model in there has zero capacitance.