lucid always block with timing parameters

Yes and no.

By their very nature “always” blocks don’t have clocks. They are “always” running, but you can use your new clock to clock DFFs.

You need to instantiate it in your top-level module and then hook up the 100Mhz clock input and use the new clock output.

Note that you CAN’T use the 100MHz input clock for anything else due to internal FPGA routing restrictions. If you need 100MHz and your other clock, you need to setup the clocking wizard to output two clocks.