How can i use a 3 V LED switch in an application that requires more
You could possible use a AMS1117 regulator to power the 3v LED (http://www.advanced-monolithic.com/pdf/ds1117.pdf). Just take the 5-7v output from your momentary switch as the input to the AMS1117 and the output of the AMS1117 to the LED. Common ground. You possibly wouldn't need the capacitors either as these are for smoothing the output for logic circuits. Small spikes shouldn't hurt your LED.