Manually choose frequencies for osmotrx

Hello. I am working on setting up an osmoTRX based base station. Where I am in the US, between 902 and 928 MHz is part of the ISM spectrum, and unregulated. Therefore, I would like to configure my base station to use both an uplink and down link frequency within this range. However, none of the pre-existing ARFCN options have both the uplink and downlink frequencies within this band. Is it possible to manually shift the frequency used by the base station, or manually select the up/down frequencies so that both remain within this range? Thank you for your help, Enzo Damato