How viable is this plan.

I was accepted into scholars although I wanted honors.
Does it make sense to do the scholars program for 2 years and then get departmental honors for the last 2 years.
Could i do all that while still pursuing the 5 years combined bs/ms for computer science.

Yes, you can. Departmental Honors is worth it. Best wishes!

Congratulations on your acceptance into the University of Maryland and into Scholars. Many students do Scholars their first two years and then apply for and do departmental honors. I say this generically speaking. The question about how honors requirements match up with the bs/ms program you should put to the department.

Here is link for departmental honors requirements for CompSci http://undergrad.cs.umd.edu/departmental-honors-requirements and here is the bs/ms info http://undergrad.cs.umd.edu/combined-bsms-program

The way the bs/ms in 5 years works is that you take 3 graduate classes (9 credits) during your senior year that double count for undergrad and graduate requirements.