I don't believe there is, although rogues can take Ninja tricks, which are kinda monk like.
Look, there's not a good way around modifying the different abilities, Frodie. Make a copy of a Monk Custom Ability, High Jump for example. It has an Expr-req that says:
#levelcount[Monk] >= 5
What that is doing is counting the number of Classes.Monk tags are on the hero, and if there are 5 or more then it is satisfied. The BAD way to solve this would be to have your archetyped class apply as many Classes.Monk tags to the hero as you have levels in that other class. Why is that BAD? Because if you do it that way, there is a widely used macro called #totallevelcount[] which will think you have more levels than you actually do, which will mess up all kinds of things.
Well what if you deleted all the Classes tags your Modern hero class applied and only applied monk Classes tags? Then #totallevelcount[] would indeed still work, but then anything that relied on counting the number of Classes tags for your original class wouldn't work anymore. I don't know that there is anything that does this, as I'm not familiar with the Modern Path data set, but it's still a bad idea to make that impossible.
Like I said, the best option is either to make your own copies of the Qinggong monk abilities and have them replace the defaults, or make your own new ones. If you were going to have them replace the default's it'd be pretty simple to change the Expr-req to a Pre-req. For example, the above expr-req would look like this as a pre-req:
Code:
~ We're valid if we've 5 monk levels
var levels as number
levels += #levelcount[Monk]
validif (levels >= 5)
~ If we lack the correct archetype (unique id arXXX) then stop here.
doneif (hero.tagis[ClassVary.arXXX] = 0)
~ Otherwise also count our levels in class YYY and see if we qualify now
levels += #levelcount[YYY]
validif (levels >= 5)
The only thing you'd have to do is fill in XXX and YYY, and adjust the number of levels you're checking against for each of those custom abilities you copied.