Creating a custom reminder time?

[Guest rumplestiltskin]

I remember doing this on my old Moto Q (but kept no documentation, shucks!). I just bought a Q9m and I need to alter the registry (I assume) in order to create a 90 minute reminder time. The Q9m jumps from 1 hr to 1 day and I need to insert a 90 minute reminder choice.

Any help is appreciated. Thanks!