E1 clock problem...

[morppheu]

Hey guys...

I need a little help with my E1 interface.
I have an internal clock and the E1 clock. When E1 chip (MT9076B) is present I use the E1 clock + E1 F0 signals, else I use the internal clock.
I want to use a DCM to lock the phase of internal clock (4.096MHz) with the E1 external clock. Is it possible?
Today I have a process to detect if E1 F0 signals is present. If its present, I switch from internal clock to E1 clock :
clk_res <= clk_int when E1_present = 0 else clk_e1;

I know its a very bad design technique, but its an old code from another guy and I am looking to make the things right.
What is the best way to interface with E1?

Can someone help me?

Thanks!