Most chargers are capable of charging at higher rates

For a 5000mah pack
Entering 5 amps as the charge rate will charge it at 1c
Entering 10 amps as the charge rate will charge it at 2c

If it doesnt allow a charge rate to be entered then simply enter double the pack size

10000 mah for a 5000mah pack

Some will allow a capacity and a charge rate as multiples of 'c' to be entered

In most cases you will be limited to the maximum charging output of the unit

Most small, cheap chargers have a 50 watt limit

Charging a 3s 5000mah pack at 1c requires 63 watts

If charged on a 50 watt charger current will be limited to 3.9 amps (50 divided by 12.6), regardless of what you enter

I use an Icharger 206b which has a 6s / 20 amp limit (300 watts)

That means I can charge a 3s pack at 20 amps (4c if the pack is 5000mah)

If I were to charge a 6s pack I would be limited to 11.9 amps (300 divided by 25.2), which would be 2c for a 5000mah sized pack

Cheers