There might be a better way to do this but you can script it pretty easily. Basically you turn on the maxscript listener, clear it out, add the modifier, make the changes and copy/paste that into a script you can then drag that script into the tool bar. Anytime you click that button you get that modifier with those…
In the lower right corner of 3dsmax right click the white or pink box and choose "open listener window" copy and paste this code into it, then highlight and drag it into your toolbar.modPanel.addModToSelection (Edit_Poly ()) ui:on$.modifiers[#Edit_Poly].weldEdgeThreshold = 0.001 [COLOR=SeaGreen]--set this number…