Possibility to use SIL connector for USB
For the link speed of 12 Mbps (FS) nearly any connector will work just fine, provided that the rest of cabling/PCB tracing maintains 90 Ohms. Although the USB 1.1 specifications do require 90-Ohm differential impedance for FS cables, the FS is not sensitive to transmission line impedance mishaps. In FS mode major reflections are ignored, since all signals are sampled in the middle of bit unit interval, where the reflections already die out more or less. More, as long as the impedance-mismatched area is shorter than 0.5-1", the reflection won't show up at all at typical FS edge rates. And as long as the D+/D- wire lengths don't differ for more than ~2 inches (skew allowance is 400 ps), it should work.

But if you have a screw-type connection (which is basically non user removable), why don't you just solder the USB cable to your board? It will be more reliable, and should even work for HS mode.