Mallet Percussion

You can add whatever text markings you want to tell the musician to produce these effects. but these sounds are not part of the General MIDI specification, so standard soundfonts won't be likely to provide them. You'll have to hunt around online to see if you can find specialty soundfonts if you want to hear those effects on playback.

There's a free SFZ bowed Vibraphone from PatchArena which is free and very good. Unfortunately, since it is SFZ, it is not fully compatible with MuseScore, but the samples will work just fine. Here's the link:
http://patcharena.com/tag/free-sfz-instruments/page/2/
(you'll have to scroll a bit to find it.)

If you're willing to make you're own soundfont from free samples, for Percussion the UIowa Sample library is hard to beat. I can also see if I can make something out of these.

For vibes:
http://theremin.music.uiowa.edu/Misvibraphone.html

for Marimba:
http://theremin.music.uiowa.edu/MIS-Pitches-2012/MISMarimba2012.html

for Xylophone:
http://theremin.music.uiowa.edu/MISxylophone.html

For Bells/Glockenspiel:
http://theremin.music.uiowa.edu/MIS-Pitches-2012/MISBells2012.html

for Crotales:
http://theremin.music.uiowa.edu/MIScrotales.html