You can do this by inserting HTML markup in the field (using a formula) and then displaying the new formula as a HTML field.
e.g.
Here's a basic Syntax formula that takes a field and adds the bold tag around the text before the colon.
dim sTmp as string
dim sLeft as string
dim sRight as string
dim sAll as string
sTmp = {yourtable.yourfield}
sLeft = (split(sTmp,":"))(1)
sRight = (split(sTmp,":"))(2)
sAll = "<b>"+sLeft+":</b>"+sRight
formula = sAll
If you place this new formula into the report and then ...
- Right Click the field and choose "Format Field"
- Change Text Interpretation to HTML Text
- Click 'OK'
There are Gotchas here. The original text is not HTML encoded, and I'm sure my example code does a simple one-line thing in about ten lines. Also, if your field has no colons in it, you'll force an error. However, it should give you the right idea.