Hi,
I think you can solder it into your PCB, or if its a double side Print-I would drill a new hole for the actuall capacitor, optionell you can solder to its one "leg" a longer wire below hes volumen...
The 4.5MHz: I dont no ... These kind of capacitors have a lot of (inter)national standard marks on it, I think its a "frequency for some measuring in accordance xxxx standard" ?...
They are RFI capacitors, but 4.5 MHz seems me to be a relative high value by a 100nF, but is not inpossible.
What for you is, in my opinion, interesting:
working voltage =250V AC,
Type =MP3 , X2/Y2
And if their has internal a serial 100 Ohm (or so) than you need some similar to find (a snubber by swithced supply) but it seems to be a simple RFI C.
Is it direct on the mains input to find? Than is these a simple "X/Y capacitor" for RFI usage...
K.