turn signal output to steady output?

The capacitor will charge instantly. I think the above diagram will work fine for you. The only thing you need to do is add a second relay to trigger this relay. The reason for that is every time you lock or unlock, you will be charging the capacitor. It will pull a few amps of current. Your alarm will not be able to supply enough current to charge the cap. Additional relay:   86 and 87 to constant power source, fused at battery. 85 to alarm lock or unlock output. 30 will feed the relay in the picture. It connects to the diode which in turn is connected to the cap and resistor and terminal 86 of the picture. I think the 10,000 mic cap will give you 1 second of output. I would use a 6 amp diode for the diode feeding the cap. If the duration is not long enough, you can add more capacitance. If the 10,000 = 1 second 20,000 will yield 2 seconds. You must use the second relay.

the 1.5 min  was up to how long the  528T  out put can be set to.          and unless your wanting to hit your unlock/lock button every few secs to keep a constant out put coming out of the ralay i would try looking up latching relay schem.life is a comedy to think, a tragedy to feel