152 bit WEP Encryption

RouterOS currently supports 40 bit (64 bit) and 104 bit (128 bit) WEP encryption.

I am looking to replace approximately 50 AP’s equipped with 152 bit WEP encryption (802.11a). The AP’s service approximately 2500 clients so re-configuring each client to a different encryption method/configuration is not a viable option.

Is there any way to modify the existing router OS configuration to allow for 152 bit WEP encryption?

Any ideas would be appreciated.