Altium has length tuning tools, so this is actually quite easy.
Just route these lines first and make everything else fit around the diff pairs.
As long as you route with (I know USB2 is 90/45 ohms...) appropriate trace impedances, and have the D+/D- lengths matched, you'll probably be fine. And if you can do this, you can equally easily match the pair lengths.
If you intend to sell this, then you will need to try to meet the layout recommendations as well as possible. Diff pairs are very prone to DM-to-CM conversion and cause EMI/EMC issues.
USB.org have test meet-ups (but being in NZ, I havent been able to use this)
If you have a professional EE CAD software package you should have no trouble.
Also, there's a high speed diff pair routing tutorial video on YT from a TI guy, that's pretty good.