I took a look at the datasheets for these two servos- They are both happy with 5V supply and their PWM ranges fall within the min and max specified by the 1061, so they are compatible. You'll have to use setMinPulseWidth and setMaxPulseWidth so the library knows what signal to output for any given position.
The reason you can't find min/max pulse widths for this servo is because it's a continuous rotation servo, so instead of having specific pulse widths corresponding to it's min and max position, it has one "center" pulse width that corresponds to "stopped" and anything higher or lower will result in forward or reverse rotation, respectively (at increasing speed as magnitude increases).
A quick google search tells me that the center pulse width for the HSR-2645CR is 1500 usec, which falls between the 1061's min and max pulse widths (83ns to 2.7ms)
