No, if the input is used as pusle measurement then it cannot be used as high speed counter anymore. You can feed the input from to both input #3 and #5 and use the second channel of HSC for counting distance.
There is no simulation for pulse measurement function. Input #3 on the TRiLOGI is purely a digital input only. On the M-series PLC the it happens to share the pulse measurement input with input #3 but in other PLCs design in future this may not always be the case.