Hi Victor,
Say you have a SimBiology model m1 in the workspace.
To find all the parameters:
allParameters = sbioselect(m1,'Type','parameter')
To find a parameter named p1:
p1 = sbioselect(m1,'Type','parameter','Name','p1')
To find several parameters:
params = sbioselect(m1,'Type','parameter','Name',{'p1','p2'})
Hope it helps, Joe